Toxicity of moniliformin and fumonisin B-1 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 monilifor min with or without fumonisin B-1. Channel catfish (average initial weight, 1.5 g) were fed diets formulated to contain 0, 20, 40, 60, and 120 mg moni liformin/kg; 0, 20, and 40 mg fumonisin B-1/kg, or two combinations of moni liformin and fumonisin B-1 for 10 wk. Fish fed diets with the lowest concen tration of moniliformin or fumonisin B-1 (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. Ove rall mortality of fish was 4% and not related to treatment effects. Hematoc rit was significantly (P < 0.05) lowered by 60-mg moniliformin/kg diet or 4 0-mg fumonisin B-1/kg diet. Dose-dependent increases in serum pyruvate conc entration and ratio of free sphinganine to free sphingosine were obtained w ith increasing concentration of dietary moniliformin and fumonisin B-1, res pectively. Mean serum pyruvate level was significantly (P < 0.05) higher in fish fed the diet containing 60-mg moniliformin/kg diet. Addition of fumon isin B-1 (40 mg/kg) to the diet containing 40-mg moniliformin/kg significan tly increased the serum pyruvate level above that of the control. Also, the lowest concentration of fumonisin B-1 (20 mg/kg diet) significantly (P < 0 .05) increased the ratio of sphingolipids. Combinations of moniliformin and fumonisin B-1 at levels of 20:40 and 40:40 mg/kg diet did not significantl y change the effect of fumonisin B-1 on the ratio of sphingolipids. The onl y tissue lesions observed in liver and heart were smaller nuclei of cells i n livers of fish fed diets containing the two highest levels of moniliformi n and the combinations of the two toxins.