A threatened giant fish named pirarucu returned to the lakes of Medio Jurua in Brazil after the constant efforts of the local fishermen and researchers. Pirarucu is a rare and mammoth size fish that is mainly found in the Amazon basin. It weighs up to 200 kilos and is the largest fish species in the Amazon. The giant fish was almost extinct a few years ago due to the illegal fishing of a few businessmen. As per the law, only 30 per cent of the pirarucu can be fished in the following year and the rule helped along in increasing the population of the fish.