Thiamin requirement of channel catfish fingerlings

In separate 20 and 12 week feeding studies, channel catfish fingerlings were fed semipurified diets containing five levels (0, 2.5, 5.0, 10.0 and 15.0 mg/kg) and six levels (0, 0.5, 1.0, 2.5, 5.0 and 10.0 mg/kg) of supplemented thiamin hydrochloride respectively. The dietary thiamin level required to provide maximal growth and prevent deficiency symptoms in channel catfish fingerlings was found to be approximately 1 mg/kg of diet. Fish fed unsupplemented diets (thiamin content of less 1 mg/kg diet) demonstrated anorexia, extremely poor growth, dark coloration of the skin and increased mortality rates. Neurological symptoms were not observed. Histological examinations of the heart, hepatopancreas, kidney, lateral muscle, gastrointestinal tract and gills of deficient fish revealed no abnormalities.