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This study aimed to evaluate the growth performance and fin regeneration rates of zebrafish fed with diets containing levels of vitamin C (Vit C). A basal practical diet was formulated to test six levels of Vit C supplementation (0, 75, 150, 300, 600 and 1,200 mg kg−1). A total of 504 juvenile zebrafish were distributed into thirty‐six 8‐L aquaria, constituting an experimental design with six treatments and six replicates. After 60 days of feeding, growth performance was evaluated. To analyse the regeneration rates of the caudal fin, 18 fish of each treatment were anesthetized and had part of their fins amputated. To determine the regenerated portion on Days 5, 10 and 15 postamputation, six fish of each treatment were subjected to image analysis. The average weight gain, specific growth rate, feed conversion ratio and final length were positively affected (p <.05) by Vit C supplementation. The diets with higher dietary concentrations of Vit C presented the best results regarding tissue regeneration. Based on the broken‐line regression analysis, it is concluded that the Vit C nutritional requirement for the maximum growth and tissue regeneration of zebrafish juveniles fed with practical diets for 60 days were 188.7 and 897.4 mg kg−1 diet, respectively. [ABSTRACT FROM AUTHOR]

Vitamin C or ascorbic acid (ASA) is an essential micronutrient for normal growth, antioxidant capacity and immunity of fish. However, appropriate requirements of ASA for Ctenopharyngodon idella, grass carp juveniles (8.46 ± 0.19), remain unknown. For this purpose, a feeding trial of 60 days was conducted in triplicates. Six isolipidic and isoproteic diets containing 0, 25, 50, 100, 200 and 400 mg/kg of ASA were prepared. Results showed a linear increase in growth as ASA supplementation was increased from 0 to 100 mg/kg. However, a further increase in dietary ASA supplementation from 200 to 400 mg/kg resulted in a slight decrease in growth parameters. A similar trend was also recorded for the whole body, proximate composition, antioxidant enzymes and organ indices against ASA supplementation. On the contrary, fish fed with basal diet had higher thiobarbituric acid reactive substances (TBARS) content in the liver and muscles than those fed with ASA supplemented diets. ASA concentration in muscles increased in a dose‐dependent manner, while ASA value was the highest in the fish fed with 100 mg/kg ASA concentration. The weight gain (WG%) data were subjected to broken‐line regression analysis, and the optimal ASA requirement of grass carp juveniles was estimated to be 67.1667 mg/kg. Taken together, the inclusion of 67.1667 mg/kg of ASA is recommended in the feed of grass carp juveniles for optimum growth performance. We also recommend analysing the effect of ASA in combination with vitamin A and E. [ABSTRACT FROM AUTHOR]

A 14‐week feeding trial was conducted to determine the effects of dietary L‐ascorbyl‐2‐polyphosphate on the growth performance, haematological parameters, biochemical characteristics, and skeletal features of juvenile hybrid grouper (♀Epinephelus fuscoguttatus × ♂E. lanceolatus). Eight experimental diets containing graded vitamin C (VC) levels (0, 18, 45, 78, 144, 245, 386, and 762 mg/kg) were prepared and fed to triplicate groups of fish (initial body weight: 10.41 ± 0.06 g). The final body weight, weight gain rate, specific growth rates, and fish survival increased when fed with diets supplemented with VC regardless of the supplementation level. Total feed intake reduction was observed in fish fed non‐VC diet. Whereas no significant differences were detected in the feed conversion ratios and protein efficiency ratios among fish treatments. The hepatic VC concentration was positively correlated with dietary VC supplementation and reached a plateau when supplemented with more than 386 mg/kg diet. Higher total protein and alkaline phosphatase levels in blood serum and incidence of skeletal deformities were recorded in the fish fed with a control diet compared to other treatments. The results indicate that adding 18 mg/kg of VC is optimum and further increase does not provide any significant benefit to fish growth and health. [ABSTRACT FROM AUTHOR]