Why fishes are not salty though they live in salty sea water?  

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trophyhunter1 | College Teacher | (Level 1) Educator Emeritus

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Since saltwater fish are surrounded by the ocean which contains high concentrations of solute as compared to inside their own tissue, their bodies tend to lose water to the environment via their gills due to osmosis. To prevent dehydration, they must constantly replenish their water supply thus they must constantly take water in by drinking it. However, their kidneys and specialized cells in the gills must remove the excess salt to prevent them from dehydrating.