The Chalakudy River is known for its diversity, as it contains 98 species of fresh water fishes out of the 152 species known from Kerala. Among these, 35 are endemic species of the Western Ghats and 31 are either vulnerable (11 species), endangered (16 species) or critically endangered (4 species) from indiscriminate collection for the aquarium fish trade, overfishing, pollution, dams and introduced species. According to a report of the National Bureau of Fish Genetic Resources in Lucknow, Chalakudy could well be the richest river in fish diversity in India, with thick vegetation on both sides.