Effect of aflatoxin-contaminated feed on morbidity and residues in walleye fish.

The effect of aflatoxin in the feed on the morbidity and toxin residue in the musculature of walleye fish was studied. The fish were divided into 3 groups of 12 each; group 1 served as controls, groups 2 and 3 received feed treated with 50 or 100 ppb toxin for 30 d respectively. Fish were kept in glass aquaria, 4 fish/aquarium, with aerator and solids-waste filter system. Fish were observed for morbidity and mortality. Six fish from each group were sacrificed after 30 d and examined for gross pathological lesions and histopathological changes. In addition, fish musculature were analyzed for aflatoxin. One out of 16 (8%) of the fish fed 100 ppb aflatoxin in 48 h. Pale livers and significant degenerative changes were observed in both toxin-treated groups. Aflatoxin B1, G1 and G2 were detected in the musculature of both groups at a concentration of 5, 10, 15, 20 ppb respectively. After 2 w of aflatoxin withdrawal, no aflatoxin was detectable in the fish muscle. However, marked histopathological lesions were still observed.