Different concentrations of ascorbyl-2-monophosphate-magnesium as dietary sources of vitamin C for seabass, Lates calcarifer

In this study, the effects of different concentrations of ascorbyl-2-monophosphate-magnesium (APM; 0, 30, 60, or 100 mg kg −1 diet) were tested in seabass for 6 weeks. Fish fed the diet without vitamin C supplementation showed various clinical signs such as fin erosion, erratic swimming behavior and spinal deformities. Several pathological changes were found in the gills and kidneys of fish fed a diet deficient in APM. The most remarkable feature in the gills was deformation of the outer epithelial cell layer, separation of the epithelial tissues of the secondary lamellae, and hyperplasia of the respiratory epithelium. An accumulation of red blood cells in the space between the outer and inner layer of epithelial cells of secondary lamellae was also observed. Changes in the kidneys were found in fish fed the APM-free diet; these changes included swelling, deformation, and fusion of mitochondria, as well as membrane whorls of endoplasmic reticulum. Seabass fed APM-containing diets did not show any of these abnormalities in the gills or proximal tubule cells of the kidney.