Effects of Single or Mixed Dietary Supplementation of Α-Tocopherol and Ascorbic Acid on Growth Performance, Flesh Quality, Digestion Capacity and Pathogen Resistance of Golden Trevally (Gnathanodon speciosus)

This study aimed to investigate the effects of dietary vitamins E (VE) and vitamin C (VC) and the VE+VC mixture on growth performance, gut morphology, feed utilisation, and capacity against pathogens in golden trevally. The results indicated that supplementation with vitamins E and C had a significant growth rate of golden trevally. Fish fed a diet supplemented with VE, VC, or a mixture of VE and VC showed significantly reduced size variations compared to fish fed the basal diet. Fish receiving diets supplemented with VE or a combination of VE and VC had a larger perimeter ratio (PR) than those receiving the control diet. Feed intake was reduced in the VE + VC group. Feed conversion ratios reduced significantly in fish fed diets supplemented with vitamins E and C. Dietary vitamin supplementation significantly influences body composition of fish. In the challenge test against Photobacterium damselae, survival rates of fish in the all three dietary supplemented treatments were significantly higher than the control diet; however, the highest survival rate was recorded in fish receiving the VE + VC combination (88.57%), followed by those fed VE (62.50%) and VC (60.87%).