Rui fish is a natural species of river system in India (mainland), Pakistan , Bangladesh and Myanmar . Found in freshwater ponds , lakes , rivers and estuaries . Wandering in different big rivers in Bangladesh, the flood enters the land during egg laying. Rui is being farmed in Sri Lanka , China , Russia , Japan , the Philippines , Malaysia and African countries due to its taste, easy farming methods and economic importance . Of the Andaman Islands Rui, which has also penetrated into freshwater rivers, is being successfully cultivated.