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Tunison Laboratory of Fish Nutrition, U.S. Fish and Wildlife Service, Cortland, NY 13045
Fingerling rainbow trout were fed semipurified diets containing graded levels of supplemental riboflavin (3, 35, 42, 49, 56, 63, 70, 100 and 600 mg/kg of diet) to determine if dietary riboflavin in excess of requirements decreases growth. In three trials with three sizes of fish (mean initial weights, 0.5, 3.2 and 4.3 g) and two water temperatures (8.3° and 15°C), no significant diet-related growth inhibition was detected. The results suggest that rainbow trout, like other animals, are insensitive to excesses of dietary riboflavin and that the growth depression reported by other workers was the result of some other dietary influence or of faulty experimental design.
KEY WORDS: riboflavin rainbow trout growth depression Salmo gairdneri
Manuscript received 13 February 1984.