Pyridoxine deficiency of grouper, Epinephelus coioides: Physiological and biochemical alteration

Pyridoxine is essential for animals. The purpose of this study was to investigate the pyridoxine deficiency symptoms and the fit dose of pyridoxine to keep normal physiological function in grouper, Epinephelus coioides. Graded levels of pyridoxine (0, 1, 2, 4, 8, 16, 32 mg pyridoxine kg¹ diet) were fed to grouper juveniles (14.83±0.31 g) for 8 weeks, and then some physiological and biochemical parameters were measured. Pyridoxine deficiency symptoms such as anorexia, poor survival, convulsion, helically swimming and hyperirritability were observed in fish fed the pyridoxine-deficient diet, and these fish also showed low whole blood haemoglobin level, liver glutamic-pyruvic transaminase (GPT) and superoxide dismutase (SOD) activities. Slight symptoms of pyridoxine deficiency also appeared among fish fed the diet with very low dose (1 mg pyridoxine kg¹ diet) of pyridoxine in 6 weeks. Broken-line regression analysis showed that the optimal pyridoxine levels for these fish to keep normal survival, whole blood haemoglobin level, liver GPT and SOD activities were approximately 1.75, 1.87, 2.22 and 2.05 mg kg¹, respectively.