Hepatoma disease, also known as liver cancer, affects rainbow trout. It is caused by the deposition of aflatoxin in the liver from the fungus Aspergillus flavus. Trout fed commercial feeds containing oil or aflatoxin-contaminated cottonseed meal are more susceptible. Symptoms do not usually appear until the disease is advanced, with liver discoloration and nodules. Control measures include using aflatoxin-free fish feed stored in dry, ventilated conditions and destroying contaminated stocks.

1. HEPATOMA DISEASE IN RAINBOW
TROUT
Presented By
Pabitra Pandey
BSc. Fisheries
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2. List of contents
• Introduction
• Symptoms
• Control measures
• References
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3. Introduction
• Hepatoma disease is also known as liver cancer
• Etiological agent: deposition of aflatoxin in liver(derived from
Aspergillus flavus)
• Trout are poikilothermous and prefer waters with temperatures from
6 to 20 C
• Hepatomas develop more rapidly in fish reared at the higher
temperatures
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4. Cont…
• Fish which are regularly feeding on commercial feeds containing oil
cause hepatoma
• Rainbow trout hepatoma was found to be widespread in hatcheries
and fish farms in 1960
• In 1961, one common denominator noted as a possible vector in
trout hepatoma was dietary oil seed meals
• Cottonseed meal from commercially pelleted fish feeds was found to
contain a carcinogenic factor
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5. Cont…
• Crystalline aflatoxins fed to trout at 0.5 to 20 ppb in a purified test
diet induced a high incidence of trout hepatoma (Halver, 1965)
• If aflatoxin levels are high (1 to 15 mg/kg body weight of aflatoxin
B1),
• Fish may die in 4 to 18 days with acute hepatitis (aflatoxicosis) before
tumors can develop
• Livers of such fish show varying degrees of hepatocyte degeneration,
necrosis and hemorrhage
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6. Symptoms
• Clinical signs are not usually apparent until the disease is advanced
• Fish may be listless and irritable, but diseased fish continue to feed
• Liver discoloration and the appearance of numerous small nodules in
the liver
• Infected liver enlarge from its normal size
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7. • Disease fish, specially female, may show distress and often die
during soon after spawning. Mortality among disease brood
stock may reach 100%
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8. Control measures
• Fish feed must be free from aflatoxin
• Need to keep it in suitable dry and ventilated storage
• Destroy the contaminated feed stock
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9. Pictures
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10. References
• Fisheries, B. O. S. (1969). The Western Fish Nutrition
Laboratory (No. 81). US Fish and Wildlife Service.
• Halver JE: Aflatoxicosis and rainbow trout hepatoma,
Symposium on Mycotoxins and Foodstuffs, 1964 Proceedings.
Cambridge, Mass, Massachusetts Institute of Technology
Press, 1965, pp 209-234
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