The present invention relates to methods of imprinting fish in freshwater with at least one odorant for the fish and causing the imprinted fish to react to the odorant in seawater, wherein the fish are maintained in freshwater prior to transfer to seawater, The method includes: adding at least one Polyvalent Cation Sensing Receptor (PVCR) modulator to the freshwater in an amount sufficient to modulate expression and/or sensitivity of at least one PVCR, the PVCR modulator being one which alters olfactory sensing of the fish to the odorant; adding feed for fish consumption to the freshwater, the feed containing the odorant and an amount of NaCl sufficient to contribute to a significantly increased level of the PVCR modulator in serum of the fish upon consumption of the feed, whereby the fish are imprinted with the odorant; transferring the imprinted fish to seawater; and providing a source of said odorant in the seawater to which the imprinted fish are transferred, thereby causing the imprinted fish to react to said odorant. The present invention also includes methods of homing or attracting fish, as well as methods for repelling fish by modulating the expression and/or sensitivity of the PVCR in the olfactory apparatus of the fish.