The high land waters of the State have cold water and that can sustain only the so-called cold-water fishes, and hence have a fishery different from that of the plain.
Thenmala reservoir, Kulathuppuzha river, Palaruvi, Aruvikkara, Gavi, Munnar, Pookkottu lake, Malampuzha and many other streams and rivulets are the home ground of such fishes. Commercially important fishes include Salmo sp., Schizothorax sp. Acrossochellus sp, Puntius sp., etc. Over fishing, destructive fishing, juvenile fishing, degradation/ loss of habitats, pollution of water bodies, climate change, mangrove deforestation, sand mining, introduction of exotic fishes, infestation of aquatic weeds, shrinkage of water resources etc. pose serious threat to fish diversity and abundance in the inland water bodies of the state.