The correct options are
A combination of five to six species of fish are used.
B all the fishes are reared in a single pond.
C fishes do not compete with each other for food.
D nutrients present at all the levels of the pond are used.
Composite fish culture involves combination of five to six species of fishes and all are cultured in a single pond. Fishes are selected in such a way that they have different food habits and do not compete with each other. As a result nutrients present in all levels of the pond are used up. Usually, fishes like Rohu, Catla, Mrigal, Grass carp, Chinese carp are used. This increases the per hectare production of fish.