Water Quality Characteristics and Physiological Responses of Fish Held in Recirculating Systems

摘要

Lethal and sublethal concentrations of ammonia and salinity for channel catfish held in recirculating systems were studied in relation to environmental calcium levels. Environmental calcium had no effect on the renal excretion of water or of any electrolytes except calcium. Plasma and muscle electrolytes from fish acclimated to fresh water or 7.5 g/liter sodium chloride were similar, but electrolyte levels increased dramatically in fish acclimated to 11 g/liter sodium chloride at both 10 and 23C. No influence of environmental calcium was observed when fish were acclimated to sublethal salinities. Addition of calcium reduced mortalities in fish exposed to normally lethal salinities.