Toxicity of Moniliformin and Fumonisin B1 Fed Singly and in Combination in Diets for Young Channel Catfish Ictalurus punctatus

.— Growth, histological lesions, and biochemical changes were investigated in channel catfish Ictalurus punctatus fed various concentrations of moniliformin with or without fumonisin B1. Channel catfish (average initial weight, 1.5 g) were fed diets formulated to contain 0, 20, 40, 60, and 120 mg moniliformin/kg; 0, 20, and 40 mg fumonisin B1/kg, or two combinations of moniliformin and fumonisin B1 for 10 wk. Fish fed diets with the lowest concentration of moniliformin or fumonisin B1 (20 mg/kg diet) had significantly (P < 0.05) less weight gain than the control fish. Increasing the level of moniliformin in the diets resulted in a linear decrease in weight gain. Overall mortality of fish was 4% and not related to treatment effects. Hematocrit was significantly (P < 0.05) lowered by 60-mg moniliformin/kg diet or 40-mg fumonisin B1/kg diet. Dose-dependent increases in serum pyruvate concentration and ratio of free sphinganine to free sphingonine were obtained with increasing concentration of dietary moniliformin and fumonisin B1, respectively. Mean serum pyruvate level was significantly (P < 0.05) higher in fish fed the diet containing 60-mg moniliformin/kg diet. Addition of fumonisin B1 (40 mg/kg) to the diet containing 40-mg moniliformin/kg significantly increased the serum pyruvate level above that of the control. Also, the lowest concentration of fumonisin B1 (20 mg/kg diet) significantly (P < 0.05) increased the ratio of sphingolipids. Combinations of moniliformin and fumonisin B1 at levels of 20:40 and 40:40 mg/kg diet did not significantly change the effect of fumonisin B1 on the ratio of sphingolipids. The only tissue lesions observed in liver and heart were smaller nuclei of cells in livers of fish fed diets containing the two highest levels of moniliformin and the combinations of the two toxins.