Principles of Genetics and Breeding

13.1.7.1.4. Cross breeding in grass carp

Grass carp has become an important cultivated freshwater fish in Asian countries and elsewhere in the world because it feeds primarily on aquatic and terrestrial grasses. But it is particularly susceptible to haemorrhagic disease, causing a great loss in farm production.

Cross breeding of Xinguo red carp (female) x grass carp (male) was done to produce tetraploidy F₁ hybrids (4n F₁).

The rationale was that common carp are not susceptible to haemorrhagic disease. Crossing sexually matured 4nF₁ and grass carp, resulted in backcrossed triploid hybrids. These hybrids are fertile and produced offspring.

However, the study in hybridizing distantly related fish, producing heterogeneous tetraploids, and back crossing to produce fertile triploids, is of great significance to the artificial manipulation of ploidy in fishes.