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

Abstract. Rainbow trout exposed to environmental free C0 2 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 CO 2 concentrations. The condition was characterized by calcification and granuloma formation in kidney and stomach. Diet, but not water, PO 4 ‐P concentration appeared to modify the prevalence and severity at each CO 2 concentration tested.