Dietary vitamin C requirement of hybrid striped bass Morone chrysops female x M-saxatilis male

A feeding trial was conducted to determine the dietary vitamin C requiremen t of juvenile hybrid striped bass Morone chrysops x M. saxatilis. Fish were fed a semi-purified basal diet with 40% crude protein and an energy to pro tein ratio of 8 kcal/g for a conditioning period of 2 wk. This diet which w as not supplemented with vitamin C contained approximately 6-mg vitamin C/k g. Following conditioning, fish (approximately 0.55 g initial weight) were stocked as groups of 20 in 38-L, aquaria and fed the basal diet and experim ental diets supplemented with 10, 20, 30, 45, 60, 75, or 150-mg vitamin C/k g as ascorbate polyphosphate for a period of 10 wk. Fish fed the basal diet and the diet supplemented with 10-mg vitamin C/kg exhibited signs of vitam in C deficiency including suppressed weight gain, reduced plasma and liver ascorbic acid levels, and abnormalities in isthmus cartilage formation. Pla sma and liver ascorbic acid levels generally reflected dietary supplementat ion with the lowest levels occurring in fish fed the basal diet and higher levels in fish fed the supplemented diets. The minimum dietary requirement (+/- SE) based on non-linear least squares regression analysis of weight ga in was 22 (+/- 6) mg vitamin C/kg diet.