Dietary niacin requirements for channel catfish.

Channel catfish fingerlings were fed purified diets containing five levels (0, 25, 50, 100, and 150 mg/kg) and six levels (0, 5, 10, 25, 50, and 100 mg/kg) of supplemental niacin in 20 and 12 weeks feeding studies, respectively. The dietary niacin level required to provide maximal growth in rapidly growing channel catfish fingerlings was found to be approximately 14 mg/kg of diet. Fish fed unsupplemented diets (niacin content of 1.6 mg/kg diet) demonstrated poor growth, anemia, skin and fin lesions and hemorrhages, exophthalmia and total mortality in 20 weeks. Mortality and gross deficiency signs were prevented by 11.6 mg niacin/kg diet and anemia was prevented by 6.6 mg/kg. No histological abnormalities were observed in the heart, hepatopancreas, kidney, lateral muscle, gastrointestinal tract and gill tissues of deficient fish.