Excessive nutrients in a fresh water body cause fish mortality. Give two reasons.  
 

Dear student,

Excessive nutrients in a freshwater body cause fish mortality. Two reasons may be - 
1) Increasing nutrients in water cause the formation of algal bloom over the surface of water which restricts the penetration of oxygen into the water.
2) By the formation of algal bloom, it increases the BOD of the water body which is the main cause of mortality of fishes.

Regards.