The invention relates to methods, compositions and kits for improving the raising of pre-adult anadromous fish, or preparing pre-adult anadromous fish for transfer to seawater. The methods involve adding PVCR modulators (e.g., calcium and/or magnesium) to the freshwater 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 contains an amount of NaCl sufficient to contribute to a significantly increased level of the PVCR modulator in serum of the pre-adult anadromous fish.