Nephrocalcinosis in rainbow trout Salmo gairdneri Richardson; the effect of exposure to elevated CO2 concentrations

Rainbow trout exposed to environmental free C02 concentrations ranging from 12–60 mg/1 for a minimum of 275 days developed nephrocalcinosis. Gross, histopathological and chemical examinations demonstrated that prevalence and severity of nephrocalcinosis increased with increasing CO2 concentrations. The condition was characterized by calcification and granuloma formation in kidney and stomach. Diet, but not water, PO4 ‐P concentration appeared to modify the prevalence and severity at each CO2 concentration tested.