Rohu is the most popular food fish in Bangladesh. It is a first growing fish in rivers and even in ponds and other closed water bodies.Now-a-days, the natural habitats are being destroyed due to anthropological effects such as urbanization, overfishing and other developmental activities. Alongside, the hatchery originated rohu fish are often being hybridized with the catla and mrigal to increase production. The ignorant hatchery operators produce seedlings by uncontrolled breeding through interspecific and intergeneric hybridization that cannot ensure expected growth rather loss their genetic quality. As a result, the purity of rohu stocks is being gradually lost. It is important to reveal that the chromosomal studies and karyotype analysis of wild and hatchery rohu populations to identify pure and hybrid rohu, to prevent loss of genetic variation i.e. DNA erosion and protect them from endangered situation.