Question

What will happen if mouth of fish is kept close?? why???

Answer 1

The fish would then die because of lack of oxygen. Unlike us humans, who respirate by using either their nose, or their mouth (occasionally), fishes need to use both their mouth and their gills. They take in oxygen-rich water through their mouths and pumping it through the gills, they leave out the oxygen-poor water out of the pharynx.

Answer 2

Answer:

if the mouth of fish is kept close in water then fish will not be able to take water and further that water will not pass through gills from where fish separates o2 from water and will die due to lack of oxygen.