The invention relates to methods for raising marine fish in freshwater. The methods involve transferring fish to freshwater containing at least one Polyvalent Cation Sensing Receptor (PVCR) modulator in an amount sufficient to increase expression and/or sensitivity of at least one PVCR; and adding feed for fish consumption to the freshwater, wherein the feed comprises an amount of NaCl sufficient to contribute to a significant increased level of the PVCR modulator in serum of the marine fish.