Responses of juvenile golden shiner Notemigonus crysoleucas fed semipurified or practical diets with or without supplemental ascorbic acid

A 12-wk feeding trial was conducted in a flow-through system to determine w hether juvenile golden shiner Notemigonus crysoleucas have a dietary requir ement for ascorbic acid. Triplicate groups of 30 fish each weighing 0.44 g initially were fed semi-purified (casein) diets supplemented with 0 or 250 mg ascorbic acid/kg, or practical (fish meal) diets supplemented with 0 or 250 mg ascorbic acid/kg. The form of ascorbic acid used was L-ascorbyl-2-po lyphosphate. Survival was higher in fish fed the semi-purified diet with 25 0 mg ascorbic acid/kg than in those fed the unsupplemented semi-purified di et, while weight gain did not differ between treatments. Weight gain was hi gher in fish fed the practical (fish meal) diet supplemented with 250 mg as corbic acid/kg than in those fed the unsupplemented practical diet, while s urvival did not differ between treatments. No other signs of ascorbic acid deficiency were observed, but fish fed the casein diets had skin and fin er osion indicative of a possible bacterial infection. Whole-body concentratio ns of ascorbic acid (total, reduced, and percent of reduced ascorbic acid) were higher in fish fed semipurified or practical diets supplemented with 2 50 mg ascorbic acid/kg than in fish fed unsupplemented diets. Golden shiner s appear to require a dietary source of ascorbic acid for growth or surviva l, depending on experimental conditions. The two main differences in the st udy were in diet composition (semi-purified versus practical diets) and app arent health status of fish fed the different diet types. Additional studie s are needed to define requirements further.