Do fish need to drink water?

Do Fish drink water????

 

The answer is Yes and NO.

But how??

Here we have to consider both Freshwater fish and salt water fish

In case of Freshwater fish: 

1.  Freshwater fish is surrounded by water having low concentration when compared to its body.
2. As a result, water is drawn into its body through the process of Osmosis.

         (Definition of Osmosis: The process of movement of solvent from low concentration                          to high concentration through a semi permeable membrane is called osmosis)

                      Semi permeabe membrane allows only certain substances to pass through. For                        example if you want to separate this membrane you can do it with Egg. 

     3.  Now if the fish doesn't excrete water, it will explode. so it must excrete water actively.

In case of salt water fish:

1.  Salt water fish is surrounded by water of high concentration.
2. Hence according to the principle of osmosis, water is drawn out of the fish body.
3. So it has to take in water to avoid drying out.