en fish disease fish disease پژوهشي Orginal research papers <p> In the present study, the impacts of various concentrations of Aflatoxin B₁ (AFB₁) on Beluga, <i>Huso huso, </i>under controlled conditions were investigated. Belugas (120±10g) were fed on diets containing 0, 25, 50, 75, and 100 ppb AFB₁/kg of diet for 3 months. Results showed various levels of AFB₁do not significantly affect the specific growth ratio (SGR) (P<0.05) of fish in different treatments. However, weight gain and food conversion ratio (FCR) were varied significantly (P<0.05 between control and treatments with diets contaminated with 75 and 100ppb AFB₁/kg after 90 days). The increase AFB₁ level of did not affect on the percent of survival rate(SR) and no mortality was observed in treatments (SR=100%) suggesting that various AFB₁levels under experimental conditions of the present study affect some growth factors, such as, weight gain and FCR but have no significant impact on SR and SGR. Histopathological studies showed that different level of AFB₁ can cause broad range of change in liver tissue, including progressive fat deposition, hepatocyte degeneration and necrosis, particularly at concentration of 75 and 100ppb AFB₁/kg of diets after 60 days. </p> Huso huso, AFB1, FCR, SGR, SR, Pathology, Liver 141 150 http://jifro.ir/browse.php?a_code=A-10-1-26&slc_lang=en&sid=1 A. Sepahdari asepahdari@yahoo.com 10031947532846001920 10031947532846001920 Yes H. A. Ebrahimzadeh Mosavi 10031947532846001921 10031947532846001921 No I. Sharifpour 10031947532846001922 10031947532846001922 No A. Khosravi 10031947532846001923 10031947532846001923 No A. A. Motallebi 10031947532846001924 10031947532846001924 No M. Mohseni 10031947532846001925 10031947532846001925 No S. Kakoolaki 10031947532846001926 10031947532846001926 No H.R. Pourali 10031947532846001927 10031947532846001927 No A. Hallajian 10031947532846001928 10031947532846001928 No