perciform

▪ fish order

Introduction

      any member of the order Perciformes, a group of bony fishes with more than 6,000 species placed in about 150 families. The order is the largest group of fishes in the world today. Perciform fishes occur in abundance in both marine and freshwater areas of the world, ranging from shallow freshwater ponds to depths of more than 2,300 metres (7,500 feet) in the oceans. Most perciforms are marine fishes, generally found along coastal areas of tropical and temperate regions of the world.

      The order includes many of the world's most important food and game fishes, such as tunas (tuna), mackerels (mackerel), bonitos (bonito), and skipjacks (family Scombridae), billfishes (billfish) and marlins (marlin) (Istiophoridae), swordfish (Xiphiidae), sea basses (sea bass) (Serranidae), and carangids (carangid) (Carangidae), a large family that includes pompanos (pompano), jacks (jack), cavallas, and scads (scad). The freshwater food and sport fishes of the perciform order include the sunfishes (Centrarchidae) and the perches (perch) and walleyes (walleyed pike) (Percidae). Many perciforms are popular aquarium fishes.

General features

Size range

      Perciform fishes vary greatly in size, ranging from the tiny freshwater goby Pandaka pygmaea (Gobiidae) of the Philippines, which is fully grown at about 1.2 centimetres (less than one-half inch) in length, to the black marlin (Makaira indica), swordfish (Xiphias gladius), and bluefin tuna (Thunnus thynnus), which attain lengths of about 3.3 metres (11 feet). The bluefin tuna and the Indo-Pacific black marlin have been known to exceed 680 kilograms (1,500 pounds) in body weight. Generally, most percoid fishes fall within the range of 30 to 250 centimetres in length.

Distribution

      Perciform fishes occur worldwide and are clearly a highly successful group. The coral reefs of tropical seas abound with colourful perciforms, including such species as wrasses (wrasse), butterfly fishes (butterfly fish), gobies (goby), damselfishes (damselfish), blennies (blenny), and cardinal fishes (cardinal fish). The perciform order comprises a large part of the fauna of the Indo–West Pacific region, which is probably the world's richest in the variety of its fish fauna. Of the Antarctic fish fauna, approximately 75 percent belong to the order Perciformes. These cold-water perciforms include the icefishes (icefish) (family Channichthyidae [Chaenichthyidae]), known for their “bloodless” appearance, which results from the lack or near lack of red blood cells and blood pigments. Freshwater perciforms include the cichlids (cichlid) (family Cichlidae), which occur naturally in India, Africa, South America, and parts of southern North America; these fishes also have been introduced elsewhere. The perch and sunfish families are found in North America and Europe, and the European perch (Perca fluviatilis) occurs well north in Siberia.

Importance

Use as food

      Since early times, the rivers and oceans have provided man with food; fishing was one of man's earliest means for securing food. Archaeological findings among shell mounds of Scotland indicate that the sea bream (family Sparidae) formed part of the diet of early man. The Nile perches (Nile perch) (family Latidae) have been found as mummies in ancient tombs in Egypt. The goatfishes (goatfish) (family Mullidae) appear in ancient Roman archives as one of the most highly valued food fishes, and in Japan the goatfish holds a good market and is eaten raw as sashimi or in the form of dried fish cakes known as kamaboko. In Japanese art through the ages, the fish god is shown with the “king of sea fish” under one arm; this highly valued food fish is the porgy Chrysophrys major (family Sparidae). A Japanese New Year's dinner usually includes buriko, the eggs of the sandfish Arctoscopus japonicus (family Trichodontidae).

      The perciform fishes play an important part in commercial (commercial fishing) fisheries all over the world. Isinglass, which is used in the production of jellies and also in the process of clarification of wine and beer, is obtained from fishes that include the drums (drum) (family Sciaenidae) and the threadfins (threadfin) (family Polynemidae). The skin of the wolffishes (wolffish) (family Anarhichadidae) provides a leather of fair quality. The guanin present in the skin of the Japanese cutlass fish (Trichiurus; Trichiuridae) is used in the manufacture of artificial pearls in Japan.

      Breeding and cultivation of perciforms has been successful in many parts of the world. The African mouthbreeder (Tilapia macrocephala, Cichlidae) has been successfully introduced in many areas and is valued for its rapid rate of reproduction and growth, providing a source of low-cost protein.

aquarium fishes

      Colourful and interesting perciforms are kept for aesthetic reasons by aquarists, augmenting an industry partially supported by fishes of other orders. Popular aquarium fishes of the perciform order include cichlids, butterfly fishes (Chaetodontidae), angelfishes (angelfish) (Pomacanthidae), labyrinth fishes (labyrinth fish) (suborder Anabantoidei) such as the Siamese fighting fish (Betta splendens) and the kissing gourami (Helostoma temmincki), and various gobies (Gobiidae), blennies, and blennylike fishes of the suborder Blennioidei.

      The freshwater angelfish Pterophyllum scalare and the discus (Symphysodon discus) are among the most popular aquarium fishes for breeding because of their remarkable means of feeding their young on the mucous secretions of their bodies.

Danger to human life

      A few of the perciforms are known to be harmful (poison) to man. Swimmers have been attacked by the barracuda (Sphyraena), which is a voracious fish reaching nearly two metres (six feet) in length. Perciforms possessing venom glands are also considered dangerous fishes. The dorsal spine of the weever fishes (Trachinidae) has a grooved structure containing a venom gland; in addition, there is also a stinger located on the opercular (gill cover) structure. Both the stinger and the dorsal spine can be extremely painful if stepped on in shallow waters. Similar venom-bearing structures are found in the dragonets (Callionymidae) and surgeonfishes (surgeonfish). The venomous spines in the surgeonfish are located on either side of the caudal peduncle (the narrow stalk just in front of the tail). Especially well armed are the electric stargazers (Astroscopus, Uranoscopidae), which are capable of discharging up to 50 volts of electricity from the modified muscle tissue just posterior to the eyes; in addition, they possess a venom spine just above the pectoral fins. The venom from uranoscopids has been known to cause death in man.

      Ciguatera fish poisoning (food poisoning) has been attributed to some perciforms that are otherwise considered to be excellent food fishes. Among these are certain carangids, snappers, barracudas (Sphyraenidae), surgeonfishes (Acanthuridae), groupers, and porgies. A species completely edible in one area may be poisonous in an area just a few hundred miles away. This curious phenomenon has not yet been fully explained, although it has been suggested that the source of poisoning may be a toxic form of blue-green alga passed up the food chain and thus present in the food of toxic species.

Natural history

Life history

      Many perciforms live out their whole lives in small areas, but others, especially open-ocean (pelagic) species, perform extensive migrations (migration), about which much remains to be learned. Some marine serranids, however, are anadromous (i.e., entering fresh or brackish water to spawn); some freshwater perciforms, such as certain species of gobies, enter the sea to spawn (catadromous). Tuna (Scombridae) may travel across the entire Pacific Ocean from the California coast to Japan or the reverse. Spawning in perciforms generally takes place in shallow coastal areas or in rivers and ponds among rocks, seaweeds, and aquatic plants. Paraclinus marmoratus, a clinid blenny, is known to lay eggs at times in the lumen (cavity) of a living sponge.

      Breeding behaviour among fishes of the order Perciformes is diverse. Pairing of male and female is common, although a single female may pair with more than one male, as among certain serranids, perches, and cichlids. The sexes are usually distinct, but hermaphroditism (presence of functional male and female organs in a single individual) normally occurs among certain sea basses and porgies. The young of the black sea bass (Centropristis striata) are mostly females with normal egg-laying functions; after five years, however, some of these females transform into functional males. About 11 species of sparids have been found to display hermaphroditism at one time or throughout their lifetime.

      Characteristic differences usually exist, especially during the breeding season, between sexes regarding colour, size, markings, or structure. The male is generally smaller in size (some exceptions are found in sunfishes, gobies, and blennies) and has brighter coloration of the fins and body. Black, white, green, red, blue, and silver are colours characteristic of the brightly coloured males of damselfishes (Pomacentridae), wrasses (Labridae), labyrinth fishes, and cichlids. Structural differences between the sexes vary from easily observed characteristics, such as the presence of a longer dorsal fin in the male dragonets, to less obvious characteristics, such as larger canines in the dentition of male blennies (Blenniidae) and gobies. Bands, blotches, and tinged markings may also be characteristic of the brighter coloured males, as in some wrasses. During the spawning season, males of certain species of cichlids, parrotfishes (Scaridae), sparids, and wrasses develop a swelling on the forehead that may persist throughout life. These characteristics presumably enhance the male in its breeding and courtship activities.

      Little is known of the courtship activities in most marine species of perciforms. Among those that have been studied, the male dragonet, with extended fins and gill covers, performs a display of colours while swimming repeatedly around the female. A similar courtship activity is also carried out by the fighting fishes (Betta).

      Fertilization is usually external, although internal fertilization, in which the eggs are fertilized within the body of the female, is well known in such groups as surfperches (surfperch) (Embiotocidae); and the male in such cases generally possesses an intromittent organ, which functions in the transfer of sperm to the female. Internal fertilization also occurs among some of the gobies, clinid blennies (Clinidae), and apogonids. Perciforms that undergo internal fertilization mostly are viviparous (viviparity); i.e., they give birth to live young. The number of young in viviparous perciforms varies from three to 50 in the surfperches. The larger viviparous forms, however, have been found to produce a greater number of young.

      Most perciform fishes are oviparous (oviparity)—i.e., they lay eggs that are fertilized externally. The number of eggs laid varies from a few hundred to more than 3,000,000 in a 32-pound (15-kilogram) yellowtail (Seriola dorsalis, Carangidae). Often, the eggs are released to float freely, but many species have evolved elaborate nest-building behaviour. Nest construction frequently consists merely of clearing away of a small area under rocks, which may be on the open bottom or even inside empty animal shells. The sunfishes and darters (Percidae) use their fins or body to dig a circular depression for use as a nest. Wrasses construct a nest out of stones, shells, and seaweed. Males generally undertake the task of building the nest, but in many cases both male and female share the labour.

      Most labyrinth fishes build bubble nests, the procedure being similar among members of the family. The male Siamese fighting fish takes a bubble of air into his mouth, coats it with a mucous secretion, then blows the coated bubble to the surface; this process is repeated until a bubble nest is formed. After pairing, the female allows the fertilized eggs to drop to the bottom, where the male picks them up in his mouth and blows them into the bubble nest. Many marine perciforms produce pelagic eggs (i.e., that float on or near the surface of the open sea). Almost all of the freshwater perciforms produce demersal eggs (i.e., that sink to the bottom). A certain amount of adhesiveness in the demersal eggs keeps the eggs together in clusters; the elongated shape of the clusters of perch eggs helps in securing the clusters to aquatic plants and rock bottoms. Not all eggs become attached to aquatic plants and other objects; the mature male humphead (Kurtidae) possesses a hooked structure on his forehead, to which the cluster of eggs is attached as soon as the female produces them. Oral incubation, in which the eggs are held in the mouth of one of the parents, is found in certain species of cardinal fishes (Apogonidae), jawfishes (Opisthognathidae), labyrinth fishes, and cichlids. The male, female, or both may incubate the eggs orally until they hatch, after which the young may be mouthbreeders. Similarly, guarding of the nest sites may be undertaken by the male, female, or both parents; however, males of some sunfishes, darters (Etheostoma), and the Siamese fighting fish defend their nest against intruders. In addition to guarding the nest, certain perciforms also aerate the eggs by directing a flow of water into the nest with fanning movements of the fins.

      Although there is no evidence of parental care in perciforms that produce pelagic eggs, a strong protective behaviour is shown by most perciforms that build nests or carry their eggs around with them. The male dwarf cichlid may help in the care of the young, but it is the female that looks after the eggs, removing dead eggs from the clutch. In certain other cichlids (Apistogramma species, for example) the female may help free the young from the eggs by gently chewing off the egg shells. The young of many cichlids follow their mother around and quickly enter her mouth should danger threaten. The discus and the freshwater angelfishes of the cichlid family feed their young on mucous secretions of their own bodies. The male Betta guards the young until they can swim away freely on their own.

Behaviour

Territorial activity

       territorial behaviour is found in many perciforms, especially during the breeding season, when the male, and in some cases the female, displays territorial behaviour in guarding the nest of eggs or the young; such fishes include certain cichlids, sunfishes, and darters. The young tigerfish (Theraponidae) protects a restricted area around a small hole dug by using its body; such territorial behaviour disappears when the tigerfish grows beyond a length of about nine centimetres (3¹/₂ inches). An intruder approaching the burrow of a jawfish is usually greeted by a threatening pose of flared gill covers and erected fins. Gobies and blennies are also known for their marked territorial display; peck order may be present among gobies holding territories, with the highest degree of competition between male gobies of the same size. The characteristic threats of gobies and blennies include flaring gill covers, gaping jaws, puffing of throats, head raising, and shaking of bodies. When threat displays fail to settle a territorial dispute, male gobies fight, biting and chasing each other.

sound production

      The significance of sound production among perciform fishes is not well known, but most acoustic activity seems to be related to feeding and spawning periods. The level of sound production in croakers (Sciaenidae) increases considerably in the spawning season during the hours of late evening. There is also a difference in level between day and night; this may result from their feeding time. Damselfishes produce clicking sounds during feeding time, grinding the pharyngeal teeth. Another type of sound produced during feeding can be heard when parrotfishes feed on plant material covering reefs, biting on coral with their powerful platelike teeth. Grunts produce sounds by grinding their upper and lower pharyngeal teeth; the sounds are in turn amplified by the air (swim) bladder. Croakers, however, produce sounds by vibrating muscles of the abdomen that are attached to the sides of the air bladder, amplifying the vibrations of other muscles. The tigerfishes, or grunters (Theraponidae), have a similar system for sound production.

Feeding behaviour

      Perciforms include both predator and prey species and are thus of great importance within the ecological food chains. The diverse adaptations for feeding are partly responsible for the success of this abundant order. Many of the colourful perciforms that occur around coral reefs are herbivorous fishes, the food of which consists mainly of plankton, algae on corals, and other reef vegetation; such fishes include parrotfishes, damselfishes, butterfly fishes, rabbitfishes and surgeonfishes. Among freshwater perciforms, certain species of Tilapia depend on aquatic plants for food. Most freshwater perciforms, however, are carnivorous, taking mosquitoes, insect larvae, and small insects. The larger predatory perciforms, in both freshwater and saltwater, feed on smaller fishes and even on birds and small mammals. They occupy a higher position within the food chain; examples include barracudas, groupers, tunas, and billfishes. The dolphins (Coryphaena) use their speed to catch fast prey such as flying fishes (Exocoetidae). The bluefish (Pomatomus saltatrix, Pomatomidae) is known for its voracious feeding behaviour; it feeds on open-water schooling fishes and, for unknown reasons, will continue to kill food fishes after its hunger is satiated.

      An interesting means of securing food is seen in archer fish (Toxotes, Toxotidae). The structure of the mouth in the archer fish is modified to form a groove along the roof of the mouth, against which the tongue fits to form a tube. The fish is able to direct a drop of water with remarkable accuracy at insects clinging to vegetation above the water surface. Thus bombarded, the insects fall into the water where they are quickly seized. Similar but less powerful squirting behaviour is also found in the butterfly fish. Another interesting type of feeding behaviour is seen in an African cichlid, which practices lepidophagy, the eating of scales plucked from other fishes.

      Some predators lie in wait for their prey instead of pursuing it. An outgrowth of the mouth of the stargazer (Uranoscopus scaber) acts as a lure for prey. Groupers are also known to lie in wait for prey among rocks.

      Adaptations of the mouth and jaw structure are seen in many of the perciforms. The piscivorous nandids (Nandidae) and the leaf fishes (Polycentridae) have large protrusible mouths capable of taking prey two-thirds their size, and the deeply cleft mouth of the swallowers (Chiasmodontidae) permits them to pass prey larger than themselves into their highly distensible stomachs.

Interspecific relationships

      Mutual relationships among species are found in many perciform fishes. The cleaner fishes of the wrasse genus Labroides (Labridae) are well-known for their role in the removal of parasites from larger carnivorous fishes. The larger fishes recognize the cleaner fish and will not devour it. They allow free passage into their cavernous mouths and gill chambers, in which the cleaner fish feeds upon leftovers and parasites. Each Labroides maintains a “cleaning station,” which is visited regularly by larger fishes such as groupers, eels, jacks, and snappers. A relationship of a protective nature exists in the butterfishes (butterfish) (Stromateidae), the young of which are often found among the tentacles of jellyfishes; the fishes are immune to the stings of the jellyfishes. Fry of horse mackerel and tuna (Scombridae) have been also found among the tentacles of jellyfishes. A similar relationship is seen in the clown anemone fish (Amphiprion percula), which is found among the tentacles of sea anemones. The mucous substances secreted by the anemone fish protect it from the stinging cells of the sea anemone. Some anemone fishes seek out only one type of sea anemone; others do not show any species preference. The sleepers of the genus Vireosa (Eleotridae) are usually found close to rock oysters and clams, into which they quickly disappear when danger threatens. A similar relationship exists between certain sea cucumbers (sea cucumber) (sac-shaped echinoderms of the class Holothuroidea) and cucumber fishes (Carapidae). These fishes are found among starfishes, clams, and sea urchins, as well as sea cucumbers. Some are host specific and may even parasitize the host, as in the Florida cucumber fish (Carapus bermudensis), which seeks out a specific sea cucumber of the genus Actinopyga, within which the cucumber fish makes its home. At times Carapus also feeds on the internal organs of the sea cucumber; this does not really harm the host because it regenerates the lost parts.

      The blind goby, Typhlogobius californiensis, depends entirely upon holes dug by the ghost shrimp (Callianassa) for a home, and is unable to live without its help. Other gobies are known to share holes with burrowing worms, pea crabs, and snapping shrimps.

      Certain perciform fishes depend upon imitative (mimicry) resemblance for survival. Immature tripletails (Lobotidae) will turn on their sides and float on the surface of the water, resembling dead leaves; similar behaviour is found in the leaf fish Monocirrhus polycanthus (Nandidae). Some wrasses (Labridae) resemble green algae because of their body coloration, a mixture of white, green, and brown. A remarkable mimic is seen in the case of the sabre-toothed blenny (Aspidontus taeniatus), which mimics the cleaner fish Labroides. By resembling a cleaner fish, the blenny is able to approach other fishes and surprise them by rushing in to bite off a piece of fin (see mimicry). Similar mimicry also occurs in an East Indies species of blenny that mimics a wrasse, apparently for food and protection.

Form and function

      The nature and diversity of the perciforms make a general definition of the group difficult; the most common characters are found in the large families of sea basses, mackerels, perches, sunfishes, and others. Perciform fishes usually have spines present on their dorsal, anal, and pelvic fins. The dorsal fin is usually divided into two parts, with the first part supported by one or more spiny rays; these are believed to have evolved for defense purposes. The pelvic fins are usually present, directly below or a little ahead of the pectoral fins, and they are supported by one spine and five or fewer soft rays. This position of the pelvic fins gives the perciforms an advantage in manoeuvring over short distances. The pelvic fins are lacking in some perciforms; in others, such as gobies, they are united to form a cuplike sucker; and, in the gouramis, the pelvic fin may be drawn out into long filaments.

      A diversity of mouth and jaw structure occurs in the perciforms; most of it is brought about by the various types of feeding behaviour. Perciforms usually have protrusible jaws; and in the leaf fishes and swallowers, the jaws are easily distensible. The protrusible jaw may have thick lips, as in the wrasses, or may possess fleshy projections, as in certain species of African cichlids. Weever fishes (Trachinus) and stargazers (Uranoscopus) possess jaws that are directed upward; the jaws help when capturing prey as they lie buried in the sand. The upper jaws are greatly prolonged in the swordfishes and billfishes; the significance of this feature is rather uncertain. Many of the perciform species that inhabit coral reefs have modifications of the snout and jaws; the butterfly fishes have a straight tubelike mouth for reaching food among coral crevices.

      Other structures of the perciforms have also undergone modification according to the various types of feeding behaviour. Most of the piscivores possess numerous short, fine, and pointed teeth; e.g., the perches and sea basses. Barracudas have long piercing canine teeth for holding and stabbing prey, and certain gobies and blennies characteristically have long, curved canines found in the lower jaw only. Perciforms that are either herbivorous or consumers of small invertebrates in addition to vegetation possess incisors, which are chisel-like teeth, as in certain sea breams; incisors may become fused into a beaklike structure, as in the parrotfishes. Enlarged pharyngeal (throat) teeth are present in some species of perciforms and are used for grinding and crushing hard-shelled food such as clams and snails. Tooth structure has undergone various modifications in many of the African cichlids. Herbivorous cichlids possess chisel-like teeth that are used to feed on plants and algae; the piscivorous ones have strong, pointed teeth. Cichlids that feed on the eggs and young of other species possess a highly distensible mouth with reduced teeth embedded in the gums.

Maung Wai Lin

Classification

Annotated classification

      The classification presented here is mainly that of British ichthyologist P.H. Greenwood and colleagues, published in 1966; it in turn is fundamentally that established by the British ichthyologist C. Tate Regan in 1929. Certain changes have been incorporated, based mostly on characters from the nervous system.

      All of the features distinguishing the order Perciformes are found in the fishes of the most generalized group, the suborder Percoidei, which contains the sea basses, sunfishes, perches, and fishes of many other families. As the subordinal name implies, the fishes composing it are “percoid,” or perchlike in appearance. The fishes in the other suborders have presumably evolved from a percoid-like ancestor, but some have changed so much as to hardly resemble a percoid fish externally.

Order Perciformes

 Swim bladder not connected by an open duct to the throat; dorsal, anal, and pelvic fins usually with spines; dorsal fin usually with the first or anterior part supported by spiny rays and the rest by soft (articulated) rays, the spinous- and soft-rayed portions often separated from each other so as to constitute two distinct dorsal fins, or there may be a notch in the profile of the dorsal fin that indicates the two joined portions. A fin is considered long- or short-based on the basis of the length of its attachment to the body. Pelvic fins with 1 spine and 5 or fewer soft rays, or pelvic fins absent; pelvic fins thoracic in position (i.e., placed ventrally below the base of the pectoral fins), pelvic fins sometimes ahead of pectoral fins (that is, jugular in position), or, occasionally, pelvic fins posterior to pectoral fins; pelvic girdle usually directly attached to base of pectoral girdle; caudal fin with not more than 17 principal (branched) rays supporting it; skull lacking orbitosphenoid bone; shoulder girdle lacking mesocoracoid bone; jaws typically protrusible; premaxillary bone of upper jaw excluding the maxilla from the gape of the mouth. Scales usually rough-edged (ctenoid), provided with small teeth (ctenii) along their posterior edge, sometimes round and smooth (cycloid). About 6,000 species, marine and freshwater; most species along shorelines in tropics and temperate zones, and in freshwater, the number of species dropping off drastically in higher latitudes. Fossil remains from the Upper Cretaceous Period (from 101,000,000 to 65,000,000 years ago).

      Suborder Mugiloidei

 Spiny-rayed dorsal fin rather widely separated from soft-rayed dorsal; pelvic fins of 1 spine and 5 rays, not thoracic but located more posteriorly on the abdomen; scaled lateral line with nerve pattern resembling that of some lower nonperciform fishes; taste nerves of trunk like many percoids; olfactory bulbs far forward, unlike other perciforms.

      Family Mugilidae (mullets (mullet))

 Lower Oligocene to present; with a cigar-shaped, roundish body, short snout; large cycloid scales; usually numerous small movable teeth; muscular gizzard-like stomach in many species. Moderately large schooling fishes, 30 to 90 cm (1 to 3 ft) long. Less than 100 species; tropical and temperate waters, some in brackish water and some in fresh water.

      Suborder Sphyraenoidei

 Two dorsal fins, both short-based and widely separated from each other; pelvic fins some distance posterior to pectorals; pattern of trunk lateral line nerves in a rudimentary percoid pattern resembling pre-percoid patterns found in atheriniform fishes; pattern of taste nerves on trunk resembles that in atheriniform fishes; large teeth set in deep sockets.

      Family Sphyraenidae (barracudas)

 Eocene to present; large, elongated, pikelike, with long, pointed jaws and big teeth; piscivorous; probably not over 120 cm (4 ft) long; all warm seas; about 20 species; fine game fishes.

      Suborder Polynemoidei

 Pelvic fins thoracic; pectorals low on side of body, divided into an upper normal part and an unusual lower part, consisting of a number of fin rays grown out into long sensory filaments, reaching to anal fin and far beyond in some species; pointed snout; large eyes.

      Family Polynemidae (threadfins)

 Upper Miocene to present; resembling mullets in body shape and widely separated two dorsal fins, but like anchovies in ventral mouth with projecting snout, rather deeply cleft mouth, and adipose eyelids; in most warm seas, often abundant at river mouths and over sandy bottoms; about 24 species, most 30–69 cm (12–24 in.) long, but 1 giant species reaches 180 cm (6 ft).

      Suborder Percoidei

 The largest suborder both in numbers of families and in species; fishes typically of a perch or bass appearance; jaws protrusible; dorsal fin usually conspicuously spinous, often with the spinous and soft portions separated or nearly so or with a notch between them; anal fin with 2 or more spines at anterior end, occasionally with 1 spine, sometimes with more than 3 spines; pelvic with 1 spine and usually 5 soft rays; body often somewhat deep rather than elongated; territorial, bottom-oriented, investigative shorefishes with great close-quarters swimming manoeuvrability, swimming backward and forward short distances with much use of pectoral fins; great variety in adaptive design and operation of jaws; generalized predators of fishes and crustaceans in all warm seas near shores, especially in tropics; in freshwater. Almost 4,000 species, some of large size; about 90 families.

      Superfamily Percoidea (basses, perches, sunfishes, cichlids, damselfishes, and many others)

 About 60 families grouped together because they show no great morphological specialization away from the general bass, grouper, or perch kind of fish taken as a model. Most inhabit shores of tropical and temperate seas or lakes. Two aspects most obviously contributing to the success of this group are the adaptability of the protractile mouth and the detailed variety of specializations for swimming manoeuvrability in restricted areas.

      Family Scombropidae

 Pliocene to present; rare, deep-water marine (down to 600–800 m, or 2,000–2,600 ft); this and the next several families retain some features that may have been those of the most generalized ancestors of present-day percoids such as: 2 dorsal fins separate, anal fin with 2 spines, primitive pattern of taste nerves on the body and remains of a special system of lateral line nerves on the head. About 7 genera and 20 species.

      Family Acropomatidae

 Rare, deep-water marine species similar to scombropids; anus located anteriorly from normal position at front of anal fin. Light organs present; midwater depths of 300–500 m (1,000–1,650 ft); 2 species; Indo-Pacific.

      Family Apogonidae (cardinal fishes)

 Eocene to present; 2 well-separated dorsal fins; 2 spines in anal fins; midsection of body often short, with head, eyes, and caudal peduncle proportionately larger; mouth large. Males orally incubate eggs. Mostly marine species, often reddish; live around coral reefs in tropics and subtropics; nocturnal; a few species from deep oceanic midwaters 1,000–1,200 m (3,300–4,000 ft); most with special lateral line system of nerves and free organs well developed on head (among the few percoids with the system). About 200 species.

      Family Moronidae (temperate basses)

 Eocene to present. Two dorsal fins connected at their bases. Most species slim-looking basses; well-known food and game fishes such as striped bass and white basses of the genus Morone. Some species anadromous. Weight to 50 kg (about 110 lb) in striped bass. About 12 species, marine and freshwaters of North America, Europe, Africa, Australia, and the Orient.

      Families Pomadasyidae and Banjosidae (grunts)

 Eocene to present. Spinous and soft dorsal fins continuous, often notched. Resemble snappers (Lutjanidae), but teeth weaker, canines absent; sound produced by grinding pharyngeal teeth and amplified by adjacent swim bladder. Second anal spine often much enlarged; about 75 species, tropical and subtropical shorefishes, many entering estuaries; good food and game fishes.

      Family Centropomidae (snooks or robalos)

 Eocene to present. Elongated, basslike fishes; head long and sloping; sizable mouth, projecting lower jaw; 2 separate short-based dorsal fins; short-based anal fin. Oceans and estuaries of Pacific and Atlantic coasts of tropical Americas; about 8 species, 45–150 cm (about 1¹/₂ to 5 ft); good food and game species.

      Family Dinolestiidae

 One species, resembling, but not related to, the barracudas (Sphyraenidae, above). Marine; Australia and Tasmania; length to 50 cm (20 in.).

      Family Latidae (Nile perches)

 Eocene to present. Closely similar to Centropomidae. Piscivorous; freshwaters of Africa; at river mouths and along coasts in Southeast Asia and northern Australia; up to about 180 cm (6 ft) long and 140 kg (300 lb); excellent food fishes.

      Family Percichthyidae (perch trouts)

 Eocene to present. Dull-coloured, small, perchlike freshwater and marine fishes of Chile and Argentina. Dorsal fin deeply notched. About 9 species.

      Family Ambassidae (glass perches)

 Small fishes similar in body form to Apogonidae; body short, rather deep. Spinous and soft-rayed parts of dorsal fin nearly separated by deep notch. Good predators on mosquitoes; large schools in sea around river mouths and in freshwater; Indo-Pacific; about 24 species.

      Family Serranidae (sea basses, groupers, and many others)

 Paleocene to present. Variously similar to many of the percoid families mentioned above in their general spiny-rayed, perchlike appearance. Dorsal fin continuous, but may be deeply notched; spinous portion of dorsal fin with longer base than soft dorsal portion; anal fin usually with 3 spines and short-based; no scaly sheath along base of dorsal and anal fins; mouth large; pectorals broadly rounded; caudal fin usually truncate or rounded, sometimes moderately forked. About 400 species in tropical, subtropical, and warm temperate seas; some in freshwater; good food and game fishes; maximum weight to about 320 kg (700 lb).

      Families Pseudochromidae, Grammidae, Plesiopidae, Pseudoplesiopidae, and Acanthoclinidae

 Quite similar, small, darkly colourful, rather secretive coral-reef basslike fishes of tropical Indo-Pacific and Caribbean seas. An interesting specialization of numerous species is the presence of multiple horizontal, interrupted lateral lines on trunk: 1 along the back, 1 along the side, and 1 along the bottom of each side of the body. Dorsal and anal fins vary from few or no spines up to 24; long dorsal fin, sometimes deeply notched between spines with a little banner or flag of fin membrane extending up and out from the end of the spine. Together, about 40 species.

      Families Glaucosomidae and Lobotidae

 Deep-bodied perchlike fishes found in eastern Pacific Ocean, except Lobotes, which also occurs elsewhere in tropical salt and freshwater; 5 or 6 species in Glaucosomidae (pearl perches); 1 in Lobotidae (triple tails).

      Family Priacanthidae (big eyes or catalufas)

 Eocene to present. Deep-bodied, reddish, serranid-like dwellers of deeper offshore waters, toward the bottom. Jaws almost vertically hinged; carnivorous. Tropical Indo-Pacific and Atlantic; few species; 30–45 cm (12–18 in.) long.

      Family Centrarchidae (sunfishes and basses)

 Eocene to present. Moderately deep-bodied; spinous and soft dorsal fins continuous, not separate as in Percidae; more than 3 anal spines. Freshwaters of North America; only 1 species, Archoplites interruptus, native west of the Rocky Mountains; various species widely introduced elsewhere; prefer quieter waters, such as ponds, lakes, swamps; excellent game fishes; size from 30 gm (1 oz) to about 10 kg (22 lb); 30 species.

      Family Embiotocidae (surfperches)

 Miocene to present. Laterally compressed, ovate, smooth-scaled, fairly small, with small head. One long dorsal fin, depressible into a scaled sheath alongside the fin. Give birth to actively swimming young; 23 species from central Baja California to Japan, absent from Aleutian chain; most species (20) occur in California; 1 freshwater species (Hysterocarpus traski) in central California; 12–30 cm (5–12 in.).

      Families Nandidae and Polycentridae (near leaf fishes and leaf fishes)

 Small, mostly piscivorous fishes with large to huge protrusible mouths; consume prey up to ²/₃ their own length. Bodies moderate to deep, laterally compressed; long spinous dorsal fin and 3 to 13 spines in anal fin; soft dorsal and anal fins short-based and colourless, used together with colourless pectoral fin in Polycentrus and Monocirrhus in swimming imperceptibly toward prey without any evident signs of fin or body movement. Six species in freshwaters (and brackish for Nandus) from India to Malaysia; for Polycentridae, West Africa and the northeast coast of South America. Six species.

      Family Cichlidae (cichlids)

 Eocene to present. Small freshwater (a few brackish water) percoids, resembling damselfishes (below) and North American sunfishes. One pair of nostrils instead of the 2 of most fishes; spinous dorsal fin long-based; anal fin short-based, 3-spined; dorsal and anal fins often pointed at posterior ends; caudal fin usually rounded; first pelvic rays of males often elongated; lateral line interrupted. Native to Texas, Central America, South America, and West Indies; Africa; Palestine, India, and Sri Lanka (formerly Ceylon). Complicated courtship, nest-building and mouthbrooding (several genera). Over 700 species, many of them important aquarium fishes; almost 600 native to rift lakes in Africa (especially Lakes Tanganyika, Nyasa, and Victoria); a few species up to 30 cm (12 in.); 1 up to 9 kg (20 lb; genus Tilapia).

      Family Pristolepidae

 A deep-bodied, laterally compressed, small-mouthed percoid, resembling a cichlid or pomacentrid but having a patch of blunt, molariform teeth on base of skull opposite similar teeth on rear floor of mouth. Long spinous dorsal fin; anal fin 3-spined; interrupted lateral line. One species only, of unsolved percoid relationship but evidently not allied to Nandidae as once thought. Freshwaters; Burma to Indochina and Malaysia.

      Family Pomacentridae (damselfishes and anemonefishes)

 Eocene to present. Abundant, conspicuous, active little fishes, often brightly coloured, found near shores and coral reefs, mainly in tropical but a few in subtropical seas. Resemble cichlids in general appearance and, like cichlids, have only 1 pair of nostrils. Lateral line continuous or interrupted; long spinous dorsal fin; anal fin with 2 spines, sometimes 3; soft dorsal and anal fins similar; caudal fin usually forked; all fins may have pointed filamentous ends; head with scales; scales large, ctenoid; bases of unpaired fins scaled; first ray of pelvic fin somewhat elongated; floor of mouth with 1 triangular, fused tooth plate in pharynx (pharyngeal plate). Territorial and pugnacious; about 250 species.

      Family Percidae (perches, walleyes, darters)

 Eocene to present. Spinous and soft dorsal fins usually well separated; anal fin with 1 or 2 spines and short-based; scales ctenoid; bodies rather elongated. All freshwater, temperate species; perches and pike perches Holarctic with a few brackish-water species and a marine species of pike perch in parts of Black and Caspian seas; darters are native only to North America. Perches prefer quiet waters, darters running waters; pike perches occur in either and are semimigratory. Many species build nests and show parental care; size up to about 90 cm (3 ft) and 11 kg (25 lb) for walleyes; darters from 2.5 to 10 cm (1 to 4 in.). About 125 species, of which about 100 are darters.

      Family Sciaenidae (drums or croakers)

 Upper Cretaceous to present. Some species resemble cods, others resemble sea basses; most have lower jaw short or underslung, with upper jaw and snout extending beyond lower jaw; often 1 or more barbels (fleshy filaments) at tip of lower jaw. Spinous and soft dorsal fins separate; soft dorsal fin fairly long-based; anal fin small, with 2 spines (most percoids have 3 or more); lateral line continues out to posterior end of caudal fin (unusual for most percoids); air bladder often with intricate outpocketings and with muscles attached to it that operate to make resonating sounds in air bladder, hence name of drum; surface of head may be cavernous through expansion of lateral line canal system. Most species occur on slopes of continental shelf, a few around islands; most in tropics, a few in temperate waters; a few freshwater. About 160 species; size from about 100 gm to 100 kg (a few ounces to 220 lb); many are important food fishes.

      Family Odacidae (rock whitings)

 Teeth incompletely fused together making a parrot-like beak as in parrotfishes (Scaridae), but odacids are evidently not related to wrasses (Labridae), parrotfishes, or whitings (Sillaginidae), all of which they also resemble. Seven species; southern Australian and New Zealand seas.

      Family Labracoglossidae

 Resemble grunts (Pomadasyidae), to which they are allied. Five species. Easter Island to New Zealand, Australia, Japan.

      Family Sillaginidae (whitings)

 Oligocene to present. Elongated fishes with long, conical snout, small mouth; moderately long dorsal and anal fins; anal fin with 2 weak spines. About 6 species of small marine fishes of shallow water; Indo-Pacific, often in estuaries and river mouths; dig in bottom with long snouts for food.

      Family Branchiostegidae (tilefishes)

 Pliocene to present. Body elongated; large, oblique mouth with strong canines; body deep through chest region; eyes high on head at top of steep sloping forehead; single, rather long dorsal fin; fin spines weak. Moderate to large body size; about 20 species, most in shallow seas of tropics and temperate zone.

      Family Lactariidae (milk trevally)

 Miocene to present. Moderately deep-bodied, laterally compressed; mouth large, oblique; eyes large; pectorals pointed; 2 dorsal fins separated; anal fin long-based. One or 2 species marine in Indo-Pacific.

      Families Owstoniidae and Cepolidae (bandfishes)

 Eocene to present. Owstoniids are marine, deep-water fishes, basslike, but large mouth is oblique, eyes large, and dorsal and anal fins long, continuous, and high; caudal fin with long rays; body tapers noticeably. Cepolids similar, but have a long tapering body and are shallow- and deep-water fishes. Cepolids occur from Europe through Mediterranean to India, China, Japan, and Philippines; owstoniids only in Far East; few species.

      Family Mullidae (goatfishes)

 Miocene to present. Resemble minnows (Cyprinidae); have a long pair of chin barbels that usually lie flat against chin, except when in use as sense organs, probing the bottom for food. Spinous dorsal fin well separated from soft dorsal fin. Fifty to 60 species at reefs and shallow sandy or muddy bottoms near shore in tropics and warmer temperate seas.

      Family Lutjanidae (snappers)

 Miocene to present. Resemble sea basses (Serranidae), but when mouth is closed jaw slips under bony cover over preorbital area (between eyes and jaw); enlarged canine teeth in jaws; spinous dorsal fin longer than soft fin and joined to it; anal fin short-based; caudal fin usually truncate. About 250 species; marine and brackish water in all warm seas.

      Families Nemipteridae, Scolopsidae, Lethrinidae, Penta-podidae

 Resemble Lutjanidae; some with wider preorbital area under which upper jaw slips; others (Nemipteridae) with molar teeth in sides of jaws and incisors or canine-like teeth at front end of jaws. About 50 species collectively; marine, Atlantic and Indo-Pacific, especially around coral reefs; some species up to 90 cm (3 ft) long; good food fishes.

      Family Sparidae (breams, porgies)

 Eocene to present; resembling fishes of families Nemipteridae and Lutjanidae; mouth small but with a powerful dentition of incisors or canines across the front of the jaws and molar-like teeth to the sides, the teeth enlarging toward the rear of the mouth; used in crushing crustaceans, mollusks, and small fishes. About 100 species in shallow seas of tropical, subtropical, and temperate zones; most species less than 30 cm (1 ft) long, a few up to 120 cm (4 ft); important food and game fishes.

      Family Gerreidae (mojarras)

 Small perchlike fishes with compressed, rather deep, silvery bodies; they are set off from most other percoids by their highly protrusible mouths used in probing soft, sandy bottoms to catch food organisms; about 40–50 species, mostly tropical marine, a few in freshwater; abundant in American tropics and East Indian region. Resemble fishes of family Leiognathidae, but the similarity is thought to be the result of parallel evolution.

      Family Pempheridae (sweepers)

 Perchlike fishes with compressed body and a very short-based dorsal fin but long-based, low anal fin; big eyes. About 20 species in tropics of Atlantic, Indian, and Pacific oceans.

      Family Bathyclupeidae

 Resemble sweepers but apparently not related; compressed body; prominent lower jaw; single short-based dorsal fin; anal fin long-based; eyes large; mouth large. Few species; deep-sea midwaters, 400–500 m (1,300 to 1,640 ft) depth.

      Family Carangidae (jacks, scads, and pompanos)

 Eocene to present. Lateral line usually strongly arched anteriorly and the posterior part usually armed with enlarged, keeled, scutelike bony scales; second dorsal and anal fins elevated and falcate anteriorly and sometimes followed by short-based free finlets; soft-rayed portions of dorsal and anal fins preceded by separated or nearly separated free, short spines; swift-looking fishes with streamlined bodies, very constricted caudal peduncle, deeply forked caudal fin, and long, sickle-shaped pectoral fins; eyes often covered with clear eyelids; worldwide in tropics and warm temperate areas; over 200 species; most are good food and game fishes.

      Family Rachycentridae (cobias)

 Long and slender, somewhat resembling mackerels and shark suckers (remoras); may be related to shark suckers (family Echeneidae); soft portion of dorsal fin preceded by a row of short, separate dorsal spines. One species, worldwide in warm seas but absent in eastern Pacific; size up to 90 cm (3 ft) and over 70 kg (154 lb); pelagic in habit.

      Family Coryphaenidae (dolphins)

 Sleek, fast-swimming fishes of tropic and temperate open seas; speeds up to 65 km (40 mi) per hour; dorsal and anal fins long-based and low; dorsal fin begins on head; deeply forked caudal fin; long, slender pelvic fins fitting into groove on belly; young males of one species change into adults with almost vertical forehead. Two species, 1 large, up to 150 cm (5 ft) and 25 kg (55 lb).

      Family Formionidae (black pomfrets)

 Body deep, strongly compressed; dorsal and anal fins long-based and elevated at anterior end, both fins with spines rudimentary in adult fish; a few enlarged scutes at end of lateral line, a characteristic of fishes of jack family (Carangidae). One species, up to about 60 cm (2 ft); Indian Ocean to Australia and China.

      Family Menidae (moonfishes)

 Eocene to present. Body strongly compressed, triangular, very deep behind head, with edge of chest razor-sharp; anal fin very long and low, reaching forward to pelvic fins; first ray of pelvic fin long and filamentous; mouth protrusible into an upward extended tube; 1 species, less than 30 cm (12 in.) long, in Indo-Pacific seas.

      Family Leiognathidae (slipmouths)

 Oligocene to present. Small fishes; body greatly compressed, ovate; mouth small but highly protrusible into a tube pointing up or down; long dorsal and anal fins elevated anteriorly, folding down into scaly sheath lying alongside bases of the fins; exude large amounts of mucus after capture. About 25 species, mostly marine shallow-water shorefishes, some in estuaries; tropical Indo-Pacific area.

      Family Bramidae (pomfrets)

 Body deep, strongly compressed; head broadly rounded in profile; pectorals long and curved; long-based dorsal and anal fins, low, sloping back to narrow caudal peduncle and deeply forked caudal fin; mouth small, oblique; about 23 species of darkly coloured fishes in rather deep waters of open ocean; size up to 90 cm (3 ft). One species, Pteraclis velifera, with enormously high and long fanlike dorsal and anal fins.

      Family Caristiidae (manefishes)

 Rare black pomfret-like fish from midwater depth of 1,000 m (3,300 ft) over much deeper bottoms; dorsal fin begins far forward over end of cranium, high and like a mane; pelvic fins very long; 1 or 2 oceanic species.

      Family Monodactylidae (fingerfishes)

 Includes family Psettidae. Small, silvery, ovate, small-mouthed fishes of salt and brackish water, temporarily in freshwater. Pelvic fins minute; dorsal and anal fins long; anterior spines of dorsal fin short and detached. Five species, coasts of Africa to India and Southeast Asia.

      Family Toxotidae (archerfishes)

 Lower Tertiary to present. Moderately deep-bodied percoids distinguished by nearly straight line from dorsal fin to tip of jaws; jaws large, oblique; lower jaw prominent; jaws and roof of mouth adapted for expelling drops of water fired from the surface at insects on overhanging tropical vegetation in mangrove swamps. Dorsal and anal fins set far back on body; dorsal fin with 4 enlarged spines at front; 5 species, with black saddle markings or spots on dorsal surface; marine and freshwaters of tropical Indo-Pacific area.

      Family Ephippidae (spadefishes and batfishes)

 Includes Chaetodipteridae, Drepanidae, and Platacidae. Eocene to present. Body deep, orbicular, greatly compressed laterally; long-based dorsal and anal fins, usually high, especially anteriorly in young; mouth quite small. About 15 species in tropics of world, few in temperate zone; size up to 40 cm (16 in.).

      Family Pomacanthidae (angelfishes)

 Eocene to present. Body deep, laterally compressed; mouth quite small; strongly resemble Pomacentridae and Chaetodontidae (in which family they traditionally have been placed) but distinguished from these and other deep-bodied coral-reef fishes by a rather long, sharp spine projecting posteriorly from the lower part of cheek region (from the preopercle bone); profile of head from dorsal fin to tip of snout mainly convex, rarely straight, not concave as in butterflyfishes; young often differently coloured from adults; less than 100 species of conspicuous coral-reef and tropical fishes; mostly of small size, a few species up to about 45 cm (18 in.).

      Family Scatophagidae (scats)

 Eocene to present; deep-bodied, laterally compressed; small mouth; 2 dorsal fins joined at base; bases of dorsal and anal fins scaled; about 4 species; coasts of Africa to Indo-Pacific, entering brackish and freshwater; scavengers, eating decaying plant and animal remains and fecal matter, including human; size up to 40 cm (16 in.).

      Family Rhinoprenidae

 One species, recently discovered, superficially similar to Scatophagidae, but really quite different. Long free filament at front of dorsal and anal fins and 1 on pectoral fin; posterior nostril of each side of head enlarged and confluent across snout. One species over muddy bottoms at river mouths in Gulf of Papua, Papua New Guinea.

      Family Enoplosidae (old wife)

 Eocene to present. Body laterally compressed; spinous and soft dorsal fins elevated anteriorly, as is anal fin; general appearance gives impression in side view of two separate bodies joined together at midpoint; pelvic fins large. One species in rocky areas of Australian coast; size up to 22 cm (9 in.).

      Family Chaetodontidae (butterflyfishes)

 Oligocene to present. Body deep, disk-shaped; mouth small, jaws sometimes on end of small (or, occasionally, fairly long) beak; slope of forehead from dorsal fin to tip of snout is concave, never convex; spinous portion of dorsal and anal fins usually prominent; bases of dorsal and anal fins scaled. Body often marked with oblique dark bands and one or two eye-like spots. Over 100 species in tropics of world, all marine; typical of coral reefs.

      Family Pentacerotidae (pelagic armorheads)

 Resemble Chaetodontidae but with higher dorsal fin and much larger dorsal, anal, and pelvic spines; dorsal fin usually strongly elevated; head rough with exposed bony plates; snout usually elongated bearing small mouth at its end; lips with “hairy” skin. Seven or 8 species, in deeper coastal waters from South Africa, Australia, and New Zealand to Japan; size up to about 50 cm (20 in.).

      Superfamily Kuhlioidea

 Classified together under this superfamily are a number of percoid families that have in common the same pattern of main branches of a complex of taste nerves that occur on the body.

      Family Kuhliidae (flagtails and aholeholes)

 Typical percoids resembling North American freshwater sunfishes and basses; dorsal fin single, notch between soft and spinous portions; dorsal and anal fins folding into scaly sheaths along their bases; 6 species of tropical Indo-Pacific oceans, preferring brackish water and freshwater; size up to 45 cm (18 in.); good food fishes.

      Families Scorpididae, Kyphosidae, Girellidae, Coracinidae (respectively, sweeps and halfmoons; sea chubs; opaleyes; and galjoen fishes)

 All similar families recognized by combination of ovate body, small mouth, strong caudal fin that is usually weakly forked; and, especially, a spinous dorsal fin with low spines followed by a higher evenly curved or falcate soft dorsal fin; about 36 species, many partly herbivorous; tropical and warm temperate coasts in Atlantic, Pacific, Indian oceans; size usually not over 45 cm; some are good food and game fishes.

      Family Oplegnathidae

 Pliocene to present. Strongly resemble Scorpidae and Kyphosidae, but incisiform teeth of young become fused in adult to form a parrot-like beak to upper and lower jaws; these fishes are not related to true parrotfishes (Scaridae); several species of shorefishes mostly in tropics of Southern Hemisphere; size up to 60 cm (24 in.).

      Family Theraponidae (grunters or tigerfishes)

 Typical percoids of small bass type; colours dull or silvery or with horizontal dark stripes; dorsal fin notched, spinous part longer than soft part; some species make grunting sounds. Less than 25 species, Indian and western Pacific oceans and in fresh waters of Australia and New Guinea; small to medium size.

      Family Arripidae (Australian salmon; ruffs)

 Not related to true salmons of Northern Hemisphere. Rather long, slender body; deeply forked tail; moderately long dorsal fin, a notch between the shorter spinous dorsal and longer soft dorsal fin. Two species; marine, young in brackish water; shallow waters off South Australia, New Zealand, and adjacent islands; size up to 1 m (3 ft); important food and game fishes.

      Family Leptobramidae (salmon trout)

 A slender carangid-like species with large mouth, rather long-based anal fin, and a single dorsal fin placed behind the beginning of the anal fin; resembles Pempheridae but apparently is not related to it; a single species reaching 43 cm (17 in.) and about 2 kg (4 lb); off coasts of western Australia and New Guinea.

      Family Emmelichthyidae (bonnetmouths)

 Includes families Caesionidae, Erythricthyidae, Dipterygonotidae, Maenidae, Spicaridae, Centracanthidae, Merolepidae by some authors. About 25 species of 2 general body types: one with slender, elongated bodies with moderately protrusible upper jaws; the other deeper bodied and with enormously protrusible upper jaws. Some school in open waters at depths of 3–45 m (10–150 ft), others in deeper water.

      Family Pomatomidae (bluefish)

 Resembles Australian salmon (family Arripidae), but spinous dorsal smaller and separate from soft dorsal; anal fin longer; body more robust; 1 or 2 small spines before anal fin. One species, widely distributed in tropical and warm temperate seas; voracious feeder on other fishes; size up to 120 cm and 11 kg (4 ft and 25 lb); good game and food fish.

      Family Nematistiidae (roosterfish or papagallo)

 Streamlined fish resembling jacks (Carangidae); dorsal fin remarkable for spinous portion consisting of greatly lengthened spines nearly separate from each other, the fin connected by fin membrane only at their bases, except the last ray, which is free at its base. Caudal fin deeply forked; pectoral fin long, falcate; mouth rather large. One species found only on west coast of Central America, from Gulf of California south to Panama; frequents sandy shores; size up to 35 kg (80 lb); game fish.

      Superfamily Labroidea

 

      Family Labridae (wrasses (wrasse))

 Paleocene to present. Various body forms, but commonly cigar-shaped, fairly slender; snout moderately long, sometimes lengthened; dorsal and anal fins long-based and low; caudal fin truncate; especially characteristic are the noticeable lips and outcurving sizable canine teeth at ends of upper and lower jaws, the large scales and the habit of swimming around the coral reefs by “rowing” with the pectoral fins. About 300 species, many beautifully coloured and marked, often with differences of colour and pattern between sexes and between young and adults; size from 5 cm to nearly 2 m (2 in. to several ft), size up to 10 kg (22 lb); marine shallow-water fishes of tropics and warm temperate zone.

      Family Scaridae (parrotfishes)

 Eocene to present; resemble Labridae but with stouter bodies and with teeth fused to form a parrotlike beak to upper and lower jaws; large scales in regular rows; herbivorous; about 80 species, often brilliantly coloured; species separable by colour and pattern; sexes often differ in colour. Size up to 120 cm (4 ft) and 20 kg (45 lb); tropical marine fishes.

      Superfamily Gadopsoidea

 

      Family Gadopsidae (river cod)

 Slender, somewhat elongated, with longer based dorsal and anal fins than typical percoid. Characterized by very slender and fairly long pelvic fins located in front of pectoral fins; caudal fin rounded. One species, rivers of southern half of Australia; somewhat resembles Ophidiidae (order Paracanthopterygii) but apparently is a derivative of family Serranidae; size up to 60 cm (2 ft).

      Superfamily Cirrhitoidea

 

      Family Cirrhitidae (hawkfishes)

 Small colourful perchlike fishes having lower rays of pectoral fins unbranched, thick-ended, and separate from one another; small flag of skin projects from tip of each spine of dorsal fin; about 35 species; shallow coastal waters in warm seas.

      Families Chironemidae, Haplodactylidae, Cheilodactylidae, and Latridae

 Similar to Cirrhitidae; 25 to 30 marine species, mostly in shallow waters of Australia and New Zealand, some species off South America; size up to 60 cm (2 ft).

      Superfamily Champsodontoidea

 

      Family Champsodontidae

 Small, elongated spiny-rayed fishes with a small spinous first dorsal fin and rather long, soft dorsal and anal fins; pelvic fins rather large; eyes near top of head and close together; unusually large mouth, the jaw extending obliquely past the eyes; several species; carnivorous; deep waters of Indo-Pacific oceans.

      Superfamily Trichodontoidea

 

      Family Trichodontidae (sandfishes)

 Resemble codfishes, but eyes high on side of head; mouth large, oblique; lips fringed; pectoral fins with long base extending forward past pelvic fins. Two species; marine; North Pacific; to 25 cm (10 in.).

      Superfamily Trachinoidea

 

      Family Opistognathidae (jawfishes)

 Resemble Clinidae, but jaws large to huge, extending far past eye; dorsal fin long-based; spinous and soft portions continuous; anal fin long-based; body usually elongated, slender; eyes almost at anterior tip of head; pelvic fins below pectorals. About 24 species, mostly small, in shallow tropical and temperate seas.

      Family Bathymasteridae (ronquils)

 Resemble Opistognathidae, but jaws not so large; no spines in dorsal or anal fins; pelvic fins slightly ahead of pectorals; about 8 species; bottom-dwelling; coasts of North Pacific Ocean.

      Family Mugiloididae

 Includes Parapercidae and Pinguipedidae. Some resemble labrids in long dorsal and anal fins (sometimes with few spines), enlarged lips that appear to curl back, and enlarged canines at front of jaws. Body elongated, cylindrical; usually spotted and banded; eyes near top of head. Size from small up to 60–90 cm (2–3 ft); about 30 species; marine; bottom dwellers, coasts of South America, South Africa, Indo-Pacific to Japan; a few good food species.

      Family Percophiidae

 Includes Bembropidae and Hemerocoetidae, resemble flatheads (Platycephalidae); body long, slender; head flattened; eyes on top of head, close together; separate spinous and soft dorsal fins; dorsal and anal fins long-based; jaws large. About 12 species; marine, from shallow down to about 200 m; South America, Indo-Pacific to Japan.

      Family Cheimarrichthyidae (torrent fish)

 Small, resembling a cottid or sculpin (family Cottidae); eyes on top of head and close together; 1 species; freshwater streams of New Zealand; young in brackish water.

      Family Trachinidae (weever fishes)

 Eocene to present. Body elongated, compressed, deep at head end, tapering to narrow, small caudal fin; a separate short-based spinous dorsal fin with black membrane and poison glands along grooves in each spine; anal and soft dorsal fins long-based; a long spine on gill cover with poison glands along grooves of spine; eyes black in upper half, white in lower half; scales small, set in distinct oblique rows; 4 species, marine shallow water down to 90 m (300 ft); lie buried in sand with eyes and top of head showing; northern Europe, Mediterranean, Pacific coast of South America; venom very painful, even dangerous.

      Family Trichonotidae (hairfins)

 Resemble Percophiidae and Mugiloididae, but body extremely elongated and dorsal fin unusually high; snout pointed; lips fringed; dive headfirst into sand. Several species; tropical and subtropical Indo-Pacific oceans.

      Family Creediidae

 Elongated little fishes resembling Percophiidae; 2 species known; coasts of Australia, Marshall and Mariana islands.

      Family Limnichthyidae

 Resemble Percophiidae; 5 species; New Zealand, Australia, and Society, Marshall, Mariana, and Hawaiian islands; sand burrowers.

      Family Oxudercidae

 A single species from coast of Asia at Macau; relationships still in doubt.

      Superfamily Uranoscopoidea

 Eocene to present. Three families; resembling toadfishes (Batrachoididae) and weever fishes (Trachinidae). Bodies rather elongated, with long dorsal and anal fins usually with few or no spinous rays; head broad, deep, flattish on top; eyes on top of head and somewhat erectile; mouth broad, oblique; lips fringed with toothlike dermal projections that interdigitate and strain water through sand when the fishes are buried to top of head and eyes; similar fringe of skin at upper end of gill slit; pectoral fins enlarged and fanlike; pelvic fins anterior to pectorals.

      Family Leptoscopidae

 Sand-burrowing fishes; no spines in dorsal and anal fins. Three species; marine; coasts of Australia and New Zealand; size up to 30 cm (12 in.).

      Family Dactyloscopidae (sand stargazers)

 General features as described under superfamily; body elongated. Shape of pelvic fins is characteristic: each has 3 thickened segmented rays whose tips are free from the fin membrane, divergent and somewhat curled. Small fishes, mostly marine, up to about 10 cm (4 in.); burrow in sand with eyes and mouth protruding from surface of sandy bottom; 20 to 25 species in tropical America in Atlantic and Pacific oceans.

      Family Uranoscopidae (stargazers)

 Head extremely broad and deep; posterior half of body tapering to a small truncate tail fin; eyes located on top of head, projecting above surface of head; large posteriorly pointing spine on shoulder girdle above pectoral fin (found in some species); dorsal fin moderately long and either with a short, nearly separate spinous portion or spines absent; anal fin moderately long and with few or no spines; large electric organs located behind eyes of species of genus Astroscopus; the only marine teleosts with electric organs; about 25 species live buried on sandy bottoms usually in shallow shore areas; a few species are found at greater depths, to about 600 m (2,000 ft), Atlantic, Pacific, and Indian oceans; size up to about 9 kg (20 lb).

      Superfamily Chiasmodontoidea

 

      Family Chiasmodontidae (swallowers)

 Slender fishes with extremely deeply cleft mouth; large, backward-pointing teeth; dorsal fin long with spinous and soft dorsals separate; pelvic fins thoracic. Capable of swallowing and holding in their greatly distensible bellies fishes larger than themselves. About 12 species in open oceanic waters down to 500 m (1,600 ft); size up to 15 cm (6 in.); relationships in doubt.

      Superfamily Notothenioidea

 Four families of codlike or sculpinlike percoids found mainly in the Antarctic, some in cold temperate Southern Hemisphere seas near Chile, Argentina, and New Zealand; superfamily includes about 75 percent of all Antarctic fishes.

      Family Bovichthyidae

 About 15 species in subantarctic and south temperate seas, off Chile, Argentina, southern New Zealand, and southern Australia; 1 species in rivers of South Australia and Tasmania.

      Family Nototheniidae (Antarctic cods)

 Miocene to present; about 50 species, most in subantarctic waters; some species near Antarctic continent; a few in cold temperate zone, 1 species in rivers of southern South America. Mainly bottom dwellers of littoral zone, some deep-water species resemble true cods (Cottidae) and have a barbel on lower jaw; 2 species, large, up to 150 cm (5 ft).

      Family Bathydraconidae (Antarctic dragonfishes)

 About 15 species; true Antarctic fishes, occurring on coasts of Antarctic continent; body greatly elongated; usually a spatulate, pikelike snout; no first dorsal fin; live on coasts of Antarctic continent to depths of 500–700 m, a few down to 2,500 m. Size up to about 50 cm, but usually much smaller.

      Family Channichthyidae or Chaenichthyidae (white-blooded fishes or icefishes)

 Famous white-blooded fishes of the Antarctic; lack red blood cells and hemoglobin. Mostly large, up to 60 cm (2 ft) long, with scaleless body and 2 or 3 lateral lines each side; head large, snout long, spatulate, pikelike; teeth large; jaws nonprotractile. About 16 species, all in Antarctic except 1 in subantarctic; mainly bottom dwellers feeding on crustaceans and small fish; most at 100 to 200 m (330–660 ft), some to 700 m (2,300 ft).

      Suborder Stromateoidei

 Five percoidlike families with an unusual and characteristic feature, a toothed saccular outgrowth in the gullet directly behind the last gill arch. One family, the Amarsipidae, lacks the toothed saccular outgrowth in the gullet. Stromateoids may be related to fishes of the superfamily Kuhlioidea.

      Families Stromateidae, Centrolophidae, Nomeidae, Ariommidae, and Tetragonuridae

 Eocene to present; slender to ovate, deep-bodied fishes; dorsal fin continuous or spinous portion set off from soft portion by deep notch; in the most generalized species, which resemble Kyphosidae, the soft dorsal is preceded by about 6 low, stoutish spines; other species resemble Carangidae. Eyes often with adipose (fatty) tissue around them; pelvic fins absent in some species, especially in ovate species; skeleton often weakly calcified; scaly sheath along bases of dorsal and anal fins. Young often found under jellyfishes or flotsam; adults live in deeper layers of ocean over continental shelves or are pelagic; a few species close to shore, in bays, even entering estuaries; 78 recognized species, many rarely seen; some feed largely on jellyfishes; others on crustaceans, tunicates, and small fishes; many are important commercially, especially in the Orient; family includes good-tasting species such as butterfishes and pompanos. Tropics to temperate zone; never near oceanic islands; size 10–120 cm. Stromateidae, Centrolophidae, Nomeidae, and Tetragonuridae also known as butterfishes, medusafishes, flotsamfishes, and squaretails, respectively.

      Suborder Icosteoidei

 

      Family Icosteidae (ragfish)

 A single species of rare deep-sea fish of North Pacific Ocean; body highly flexible in water, limp as a rag out of water; little is known of its anatomy. Resembles Stromateidae; presumably derived from a percoidlike ancestor; no spines in fins; pelvics and scales present in young, both absent in adult; body elongated, much compressed; up to 220 cm (7 ft).

      Suborder Blennioidei

 Fairly large suborder composed of 2 groups, the tropical blennies, some of which are percoidlike, and the northern blennies. The northern blennies are eel-like fishes, but the appearance of their faces and the aspects of their fins generally resemble those in the tropical blennies.

      Superfamily Blennioidea (tropical blennies)

 All soft, articulated fin rays in the dorsal, anal, and pelvic fins are unbranched; pelvic fins, which are seldom greatly reduced, consist of 1 spine and 4 or fewer rays and are located in front of the pectoral fins; there are the usual 2 nostrils on each side of the head. Exact 1-to-1 ratio between the vertebrae and the dorsal rays and posterior anal rays; only 1 lateral line. About 620 species.

      Family Clinidae (clinids)

 Eocene to present. Percoidlike fishes, some moderately elongated, rather flat-sided, usually with somewhat pointed snouts and fleshy lips; dorsal and anal fins rather high and long-based, with fin membranes conspicuously supported by thin, riblike fin rays; caudal fin fanlike, not large; pelvic fins ahead of pectorals, slender; 1 spine and usually 2 or 3 rays; pelvics in some species appear usable in walking movements; cirri (bushy tentacles of skin) often present above eyes, on anterior nostrils, and just behind head on each side. Body scaled; scales cycloid; first 3 rays of dorsal fin often higher and more or less separate from rest of dorsal. A few species “four-eyed” (i.e., with eye divided so as to see out of water). Most inhabit tide pools, kelp, rock crevices; some species down to 30 m (100 ft); size up to 30 cm (12 in.), but most are smaller; about 180 species.

      Family Tripterygiidae (threefin blennies)

 Pliocene to present. Much like clinids but dorsal fin divided into 3 distinct parts, the first 2 of spines only; small bottom fishes of reef and rocks. About 100 species mostly in warm seas.

      Family Blenniidae (combtooth blennies)

 Eocene to present. Resemble clinids in fins and body shape but differ in being scaleless, in having a steep forehead and only a single row of teeth in both jaws, the teeth being close-set, long, comblike. Sometimes a pair of large to enormous curved “canines” farther back in jaws; some species hop about out of water in intertidal zone; fins without pungent spines; eyes large and at top of forehead; pelvic fins with 2 rays. About 300 species, in tropical, subtropical, and warm temperate seas; small size.

      Family Chaenopsidae (pike blennies)

 Pliocene to present. Body very elongated; jaws long; long gill area; dorsal and anal fins long, confluent with caudal fin; no scales or lateral line; 6 species in tropical and subtropical marine shore areas of Central America and Caribbean; small fishes living in worm tubes and burrows.

      Family Pholidichthyidae (engineer fish)

 Very elongated eel-like fish; reclusive, living under excavations; move sand and gravel in mouths; known previously only by young stage; adult recently discovered by L. Dempster. One species; marine; in tropics, Indonesia and Philippines; size up to 30 cm (12 in.); poorly known; relationships in doubt.

      Family Notograptidae

 Eel-shaped; dorsal and anal fins long-based and high, both confluent with caudal fin; pelvics 1-rayed, filamentous, placed before pectorals; body scaled, mouth large. Two small species; marine; western Australia.

      Superfamily Stichaeoidea (northern blennies)

 Eel-like fishes; single pair of nostrils; dorsal and anal fins long-based and often joined to caudal fin; pelvic fins placed a little before pectoral fins, consisting of 1 spine and fewer than 4 rays; bottom-dwelling fishes usually of littoral zone, some supralittoral; a few in deep water (down to 450 m).

      Family Stichaeidae (pricklebacks)

 Includes families Chirolophidae, Lumpenidae, Xiphiodontidae, Cebidichthyidae. Eel-like; body usually scaled; dorsal fin with spines only or some soft rays at rear of fin; pectorals reduced; pelvics present or absent; some species with 3 or 4 lateral lines but most species lacking lateral line. About 54 species, most in North Pacific, some in Atlantic; often among seaweeds when tide is out; also in deeper water (to 200 m); most feed on invertebrates, a few on seaweed; most species small, a few up to 60 cm.

      Family Pholidae (gunnels)

 Elongated; strongly compressed laterally; scaled; pelvics reduced to 1 spine and 1 ray, very small or absent; spines only in dorsal fin. About 8 species, most in North Pacific; also in North Atlantic; size small; intertidal zone or shallow water; feed on small bottom invertebrates.

      Family Anarhichadidae (wolffishes)

 Big head and long tapering body, laterally compressed; massive dentition on jaws, roof of mouth, and throat for crushing mollusks, sea urchins, crustaceans; length to 2.3 m (7.5 ft). Nine species, in northern oceans; littoral zone to 300 m (1,000 ft); good food fishes.

      Family Ptilichthyidae (quillfish)

 Extremely elongated, body ending in a free, fleshy point; pelvic fins absent; dorsal and anal fins like vanes of a feather. One species, rare; North Pacific.

      Family Congrogadidae

 Includes Haliophidae. Resembles Stichaeidae but mouth and lips large; fins almost or entirely spineless; 3 lateral lines. About 8 species; rock-dwelling, in shallow coastal waters of Indo-Pacific from Africa to Japan.

      Family Zaproridae (prowfish)

 A single species like a shorter, deeper bodied prickleback; pelvic fins absent; size up to 2.8 m (9 ft); deeper coastal waters to 350 m, California to Alaska.

      Family Scytalinidae (graveldiver)

 Eel-like, with dorsal and anal fins soft-rayed and not beginning until middle of long straight body; body appears to flare out somewhat at these fins; pelvic fins lacking. One species; marine, California to Alaska; small, to 15 cm (6 in.); burrows quickly in sand or gravel in intertidal zone.

      Suborder Acanthuroidei

 Modified percoid-like fishes characterized by peculiarities of bones suspending the jaws, which thereby are extended far forward as small nibbling mouths at end of more or less lengthened snout.

      Family Acanthuridae (surgeonfishes)

 Includes Zanclidae. Percoid-like fishes characterized by usually 1 or 2 lancet-like spines (like a surgeon's scalpel) alongside the caudal peduncle (in front of base caudal fin); body deep, compressed; dorsal and anal fins long-based; scales small; eyes high on side of head; mouth small, low, sometimes extended into a beak; teeth close-set and lobate. About 75 species; many herbivorous; inhabit shallow tropical shores, a few in deeper water.

      Family Siganidae (rabbitfishes)

 Resembling surgeonfishes but uniquely characterized by pelvic fins each having 2 stout spines, located along the outer and inner edges, respectively; both spines are grooved for carrying venom; no lancet-like spine or buckler on caudal peduncle; mouth small and rabbitlike, used for nibbling algae. About 18 marine species of small to moderate size; tropical Indo-Pacific, around coral reefs and rocky areas.

      Suborder Scombroidei

 Streamlined, mackerel-like or marlin-like fishes the interrelationships of which are in doubt; upper jaw not protrusible; maxillary bones of upper jaw more or less firmly attached to non-protractile premaxillaries that lie ahead of them.

      Family Gempylidae (snake mackerels)

 Eocene to present. Elongated, laterally compressed; mouth large, with large, cutting teeth; spinous part of dorsal fin longer than soft-rayed part, the latter often broken up into finlets posteriorly; pelvic fins usually not rudimentary. Sixteen species; tropical and temperate seas; down to 600 m (2,000 ft); length to 1 m (40 in.); some commercial value; good food fishes.

      Family Trichiuridae (cutlass fishes)

 Paleocene to present. Elongated, bandlike body; large mouth with large fangs anteriorly. Scaleless; dorsal fin long, spinous anteriorly; anal fin long-based, spines short; caudal fin deeply forked on most species, absent in some (body ending in tapered point); pelvic fins reduced to scalelike spine and 1 small ray, or absent. Fifteen species in warm oceans; rather deep water offshore, to about 1,000 m (3,300 ft); piscivorous.

      Family Scombridae (tunas and mackerels)

 Moderate to large, streamlined, swift-swimming, schooling fishes; body often thickly rounded, tapering to a narrow caudal peduncle bearing in some species 2 or 3 keels on its side; caudal fin widely forked or lunate (scimitar-shaped); distinguished from all fishes by series of separate finlets following spinous first dorsal and spinous anal fins; well-developed vascular system under skin of tunas is associated with sustained high-speed swimming and a body temperature a few degrees higher than that of the surrounding water; make extensive migrations to spawning and feeding grounds; fins fit into grooves or depressions on body; about 40 species, open waters of tropics and warm seas of world; feed on fish, crustaceans, squids, and other abundant animal life; length 30 cm to 3.3 m, weight to 800 kg. Many species subjected to ever-increasing fishing exploitation and will be threatened with extinction.

      Family Xiphiidae (swordfish)

 Bones of upper jaw prolonged into a swordlike structure, flatter and sharp-edged, as compared with the round, shorter bill of marlins and billfishes; dorsal fin high and short-based, not extending beyond middle of body; caudal fin with high lobes; second dorsal fin small; pelvic fins absent; no teeth in jaws except in very young; no scales. Probably only 1 species, Xiphias gladius, worldwide in tropics and temperate seas; from surface to 400 m; size up to 3.6 m (141 in.) and 450 kg. (985 lb.). Sword is lashed about inside schools of fishes; injured fishes are eaten. A major big-game fish; excellent eating and commercially important.

      Family Istiophoridae (billfishes, marlins, sailfishes, and spearfishes)

 Bill round and shorter compared with sword of swordfish; dorsal fin long, extending almost the length of back of body and reaching striking height in the sailfish, Istiophorus gladius; pelvic fins present as thin filaments; body scaled; 2 small keels on each side of caudal peduncle; fine teeth on jaws. About 7 species; worldwide in warm seas; all are large species, the black marlin (Makaira indica), the largest, probably attains 900 kg (2,000 lb); record for rod and reel is 710 kg (1,560 lb); greatest game fishes in the ocean, and excellent food fishes, of considerable economic importance.

      Family Luvaridae (louvar)

 One species; rare; resembles a dolphin (family Coryphaenidae) in its very high forehead and eye placed low almost on level with mouth; mouth small, toothless; body deep, laterally compressed; a fleshy keel on each side of caudal peduncle; pelagic in tropics and subtropics; length to 1.5 m (5 ft).

      Suborder Anabantoidei

 Small percoid-like fishes characterized by an accessory air-breathing chamber of labyrinthic structure on each side of head, above regular gill chamber; an unusual patch of teeth on roof of mouth, teeth which attach to floor of cranium; usually build foam nests. Freshwater fishes of Southeast Asia, India, and Africa; about 70 species in 5 families, 4 of which are closely related; the fifth, Badidae, is more generalized.

      Family Badidae

 Resembling Anabantidae externally but lacking accessory air-breathing chamber. Have special patch of teeth on roof of mouth and characteristic courtship behaviour of anabantids; 1 species, freshwaters of India and Southeast Asia; small, 5–8 cm (2–3 in.) long.

      Family Anabantidae

 Pleistocene to present; about 20 species, freshwaters of tropical Africa, Southeast Asia and Philippines; includes the “climbing perch”; size small.

      Family Belontiidae (fighting fishes, some gouramis, and others)

 About 50 species of small freshwater fishes from tropical Africa, India, Burma, Sri Lanka, Southeast Asia, Malaya; includes Siamese fighting fish (Betta splendens), various species of gouramis, which have 1 ray of each pelvic fin extended into an elongated filament; paradise fishes and other popular aquarium fishes. Most of these species were formerly placed in family Anabantidae.

      Family Helostomatidae (kissing gourami)

 Freshwater, Southeast Asia; popular aquarium fish; one species.

      Family Osphronemidae (gourami)

 Pelvic fins each with 1 ray drawn out into a long filament; 1 species; freshwater in Sumatra, Java, Borneo, grows to about 9 kg (20 lb).

      Suborder Luciocephaloidei

 

      Family Luciocephalidae (pikehead)

 Pike-like in body form and long head; an accessory suprabranchial air-breathing chamber (but not labyrinthic); bony plate in throat region; peculiar jaws. One species, freshwater; Malay Archipelago and Peninsula.

      Suborder Mastacembeloidei

 

      Family Mastacembelidae (spiny eels)

 Eel-like; head elongated with fleshy, mobile proboscis projecting beyond lower jaw; soft dorsal fin preceded by series of erectile spines. About 50 species, freshwaters from tropical Africa to Southeast Asia up to China; up to 90 cm (3 ft), but most much smaller; some attractively coloured aquarium fishes.

      Family Chaudhuriidae

 One species in freshwaters of Burma; similar to spiny eels but small and without fleshy proboscis.

      Suborder Kurtoidei

 

      Family Kurtidae (nurseryfishes)

 Peculiar, small, percoid-like; males carry eggs, stuck under an anteriorly pointing hornlike process on top of back of head. Two species; brackish water and lower parts of streams; Indo-Malaysia and New Guinea.

      Suborder Echeneioidei

 

      Family Echeneidae (remoras)

 Oligocene to present; differ from percoids mainly in having a sucking disk on top of head, modified from the spinous first dorsal fin. About 10 species; warm marine seas; ride attached to large fish or other marine animals or ships; carnivorous; some are cleaner fish for other fishes; length 30 to 90 cm (1 to 3 ft).

      Suborder Ammodytoidei

 Families Ammodytidae and Hypoptychidae (sand lances). Eocene to present. Long slender percoid-like fishes with long, pointed head and projecting lower jaw; dorsal fin long-based, with soft rays only; pelvic fins thoracic or (usually) absent. About 18 species; most seas of the world, especially colder waters; sand burrowers; large schools near shores form an important food source for many other fishes; 20–40 cm (8–16 in.).

      Suborder Gobioidei

 Almost all with pelvic fins located beneath pectorals and joined together to form a vacuum cup or suction disk; some with pelvic fins close together but not in form of a suction cup; a few lack pelvics; all lack one particular bone of cranial roof. More than 800 species, most of small size, living as bottom dwellers, worldwide, in saltwater, freshwater, or brackish water, especially in tropics.

      Family Eleotridae (sleepers)

 Pelvic fins close together or in contact anteriorly, but not united into a sucking cup; short-based spinous first dorsal fin and longer based soft-rayed second dorsal; all fins usually with rather long fin rays; no lateral line. Numerous species; found along coasts and rivers in tropics and subtropics; most 10–30 cm (4–12 in.) long, one to 90 cm (35 in.) in length.

      Family Gobiidae (gobies)

 Eocene to present. Pelvic fins united to form a suction cup; no lateral line; simple-looking but often colourful fishes with 2 dorsal fins; all fins rather conspicuously large compared with small, usually slender body; definite rows of naked lateral-line organs on head. More than 700 species; size from 1.2 cm (0.5 in., world's smallest vertebrates) to something under 30 cm (12 in.), with most less than 10 cm. Shallow coastal waters of tropics and temperate zones; usually resting on bottom or hidden; carnivorous.

      Family Periophthalmidae (mud skippers)

 Elongated gobies with blunt head; eyes erectile, prominent, on top of head; pectoral fins with muscular base used to walk over mud and climb mangrove roots; about 6 species in estuaries and mud flats of Indian and Pacific oceans, to Japan.

      Family Rhyacichthyidae (loach goby)

 Pelvic fins widely separated; head flattish, pointed; mouth ventral; 1 species living in torrential mountain streams of Indonesian Archipelago, up to Philippines; size up to 33 cm (13 in.).

      Family Gobioidae

 Elongated, eel-like gobies; dorsal fin very long, spinous part distinct from, but connected to, soft part; dorsal and anal fins confluent with caudal; eyes tiny to indistinct; mouth often obliquely upward; about 20 species, marine and brackish water of tropical America, Indian and Pacific oceans; about 8–30 cm (3–12 in.).

      Family Trypauchenidae

 Eel-like; scaled; dorsal and anal fins very long and confluent with caudal; pelvic fins united at base but not forming a cup or disk; eyes tiny. A blind cavity above gill cover opening to exterior by a pit. Burrowers in mud and gravel; about 12 species, along coasts and estuaries from Africa to Japan and Oceania.

      Family Kraemeriidae

 Rare little elongated fishes; pelvic fins separate; chin of lower jaw large, pointed, forming terminal end of head; eyes small, on top of head; 2 species, Indo-Pacific oceans.

      Family Microdesmidae

 Rare, small, eel-like; chin large, forming pointed end of snout; about 6 species; both coasts of tropical America, West Africa, tropical Pacific.

      Suborder Callionymoidei

 

      Family Callionymidae (dragonets)

 Eocene to present; resembling flatheads (Platycephalidae); body flattened, broad, muscular; snout very short; mouth small; gill openings restricted, located on top of head; eyes on top of head and close together; pelvics in front of pectorals; large spine pointing posteriorly at angle of preopercle on gill cover; bottom dwellers from tidepools down to 600 m (2,000 ft); burrow into sand; push along bottom using pelvic fins; about 40 species found in tropical and temperate zones.

      Family Draconettidae

 Look like callionymids but are separated on differences in head skeleton; no preopercular spine; a few species; North Atlantic and North Pacific in deep water.

Critical appraisal

      Classification of perciform fishes will be receiving much more study in the future. Expected changes include removal of some groups from the order, addition of some from other orders, and considerable realignment of many groups within the Perciformes. Evidence suggests removal of Gobioidei to a preperciform position, possibly as a distinct order. The snake-heads (order Channiformes) should likely be returned to the order Perciformes, associated with the anabantoid and luciocephaloid fishes. Particularly difficult problems are the relationships and classifications of trachinoid, uranoscopoid, notothenioid, and stichaeoid fishes. Studies are presently being made on possible interrelationships between clusters within the 60 or more families of percoid fishes (suborder Percoidei). The placement and relationships of the atherinoid (sometimes called percesocine) fishes are still in dispute. The present classification follows that of Greenwood et al. in the removal of Atherinidae from perciform fishes and in the removal of the ophidioid and zoarcid fishes. Support for retaining the Atherinidae in order Perciformes and for other differences in the order Perciformes has been given by an American ichthyologist, W.A. Gosline, in a series of papers published between 1962 and 1971. Questions of relationships between carangid, rachycentrid, echeneid, and scombroid fishes are still unsettled. Many large and exciting problems thus remain.

Warren Curtis Freihofer

Additional Reading

Books containing many excellent illustrations of perciform fishes and short accounts of the biology of each group include J.E. Böhlke and C.C.G. Chaplin, Fishes of the Bahamas and Adjacent Tropical Waters, 2nd ed. (1993), a well-illustrated work with keys for identifying species and excellent summaries of the biology of each family; David Starr Jordan and Barton Warren Evermann, The Fishes of North and Middle America, 4 vol. (1896–1900, reprinted 1963); T.C. Marshall, Fishes of the Great Barrier Reef and Coastal Waters of Queensland (1964), contains many colour and black-and-white pictures of perciform fishes; I.S.R. Munro, The Fishes of New Guinea (1967), 1,095 fishes illustrated by photographs, with 76 species in colour; J.L.B. Smith, The Sea Fishes of Southern Africa, 5th ed. (1970), profusely illustrated with many colour plates; J.L.B. and Margaret M. Smith, The Fishes of Seychelles, 2nd ed. (1969), 880 species illustrated, many in colour; A.C. Wheeler, The Fishes of the British Isles and North-West Europe (1969); John E. Randall, Caribbean Reef Fishes, 2nd ed. rev. (1983), contains many fine photographs of perciforms and others; Robert B. Chiasson, Laboratory Anatomy of the Perch, 4th ed. (1991).Other books with information about perciform fishes include Earl S. Herald, Living Fishes of the World (1961, reprinted 1972); N.B. Marshall, The Life of Fishes (1966); and U. Okada, Fishes of Japan, rev. ed. (1965).References pertaining to classification and relationships include W.C. Freihofer, “Patterns of the Ramus Lateralis Accessorius and Their Systematic Significance in Teleostean Fishes,” Stanford Ichthyol. Bull., 8:79–189 (1963); and “Trunk Lateral Line Nerves, Hyoid Arch Gill Rakers, and Olfactory Bulb Location in Atheriniform, Mugilid, and Percoid Fishes,” Occ. Pap. Calif. Acad. Sci., no. 95 (1972); W.A. Gosline, “Systematic Position and Relationships of the Percesocine Fishes,” Pacif. Sci., 16:207–217 (1962); “The Suborders of Perciform Fishes,” Proc. U.S. Natn. Mus., 124:1–78 (1968); and Functional Morphology and the Classification of Teleostean Fishes (1971); P.H. Greenwood et al., “Phyletic Studies of Teleostean Fishes, with a Provisional Classification of Living Forms,” Bull. Am. Mus. Nat. Hist., 131:339–455 (1966); D.E. McAllister, “The Evolution of Branchiostegals, and Associated Opercular, Gular, and Hyoid Bones, and the Classification of Teleostome Fishes, Living and Fossil,” Bull. Natn. Mus. Can., no. 221 (1968); C.T. Regan, a series of papers on perciform classification in Annals and Magazine of Natural History, series 7, vol. 11 and series 9, vol. 11 (1903–23); and “Fishes,” Encyclopaedia Britannica, 14th ed., vol. 9, pp. 305–328 (1929), which still forms the major basis of present perciform classification; D.E. Rosen, “The Relationships and Taxonomic Position of the Halfbeaks, Killifishes, Silversides, and Their Relatives,” Bull. Am. Mus. Nat. Hist., 127:217–267 (1964), and with Colin Patterson, “The Structure and Relationships of the Paracanthopterygian Fishes,” Bull. Am. Mus. Nat. Hist., 141:357–474 (1969).

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