What is stocking of fish and what is the density of stocking fish?

Fish are raised in a hatchery and then released into water bodies so as to supplement the present population or to create a new population of fish. Generally stocking is done for commercial benefits, but sometimes it is also useful in restoring the threatened species of fish. The minimum stocking density is for all different species of fish are different and it also depends on the size of the fish. For e.g., if the size of silver carp is 7-10 cm, then the stocking density is 3000 fish per hectare. Similarly, for Mrigal fish of the same size the stocking density is 500 fish per hectare.