Evolution of early hepatoma in the rainbow trout

Abstract

The evolution of hepatic microscopic nodules in hatchery rainbow trout (Salmo gairdneri) fed diets containing aflatoxin has been studied. After 13 months of feeding, the histopathological examination showed microscopic nodules in the liver of 22–26 per cent of trout, wich had been fed diets containing high levels of aflatoxin. At this time a group of trout was fed a non carcinogenic diet (fresh beef liver), for other 13 months. The trials were carried out in water with a constant temperature of 8–9°C. Even though the carcinogenic stimulus was removed, trout produced hepatic tumors in 50–54 per cent of examined samples. The authors conclude that the micro-nodules, early found in the liver of trout fed carcinogenic diet, are to be considered as true neoplasms.