Some common diseases of fish

▪ Table

Some common diseases of fish

name(s) of disease causative agent nature of disease

mouth fungus (cotton-wool disease) bacterium (Chondrococcus columnaris) funguslike disease inaccurately named, since causative agent is a bacterium; a contagious disease; produces swollen lips, loss of appetite, and a "cotton-wool-like" growth on mouth; treatment utilizes antibiotic drugs

tailrot bacteria (Haemophilus and Aeromonas species) infection may spread from fin and tail to body and cause death; disease may be controlled by surgery or use of drugs

dropsy (ascites) possibly associated with a bacterium (Aeromonas punctata) characterized by accumulation of liquid in internal organs and tissues, inflammation of intestines, and infection of liver; epidemics can occur; most treatment except the antibiotic chloramphenicol unreliable

red pest of eels bacteria (Vibrio anguillarum; Aeromonas species) Vibrio multiplies readily in salty water (1.5 to 3.5 percent) and can cause extensive blood-coloured areas on skin; Aeromonas species produce ulcers in the skin

fish tuberculosis bacteria (Mycobacterium species) symptoms include loss of appetite, emaciation (leanness), skin defects, blood spots, ulcers, and cysts (on internal organs)

eye fungus fungus infection follows damage to cornea of eye; a typical symptom is a white cotton-wool growth hanging from eye; untreated eye is destroyed within days; untreated fish die

fish lice louse (Argulus species) bloodsucking parasites on the surfaces of many fish species

skin flatworms (flukes) platyhelminth small parasites; cause skin colour to fade, blood spots, increased respiratory rate, and debilitation

bursting of the swim bladder physical agent occurs if fish in deep water rise to surface too rapidly; fatal

air embolism physical agent occurs if oxygen content of water is higher than normal, as when water temperature is higher than normal; bubbles of nitrogen gas in blood cause the disease

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