Critical review of the requirements of ascorbic acid in cold and cool water fishes (salmonids, percids, plecoglossids, and flatfishes)
Nutrient Requirements of Fish (NRC, 1993) is the standard reference stating nutritional requirements for maximum growth of major cultured species under laboratory conditions. It is intended to serve as a basis for setting minimum nutrient levels. However, for practical purposes vitamin C requirements should be considered as variable quantities depending on the criteria selected for their determination. Indeed, dietary vitamin C levels necessary to support and possibly enhance functions other than growth are also being investigated. For example, research with rainbow trout (Oncorhynchus mykiss) indicates that optimal reproduction performance, health status, and response to stressors require higher AA intakes than the amount needed for growth (Halver, 1995). Recent studies show that cellular immune parameters positively respond to enhanced cellular concentrations in vitamin C (Verlhac et al., 1995). This chapter reviews the established vitamin C requirements of salmonids, percids, plecoglocids, and flatfishes, and highlights the biological and environmental factors that may affect the dietary requirements of this micronutrient.