Anatomy: Animals Inside

Excretory System

Do freshwater fish drink water?

Freshwater fish never drink water separate from ingesting food. These fish are prone to gain water since their body fluids are hypotonic (containing a lesser concentration of salts) to the surrounding water. They drink water through their gills to maintain the correct balance of salts in their bodies and excrete large quantities of diluted urine daily. It is estimated that freshwater fish eliminate a quantity of urine equal to one-third of their body weight each day.


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