The Indian fish fauna is divided into two classes, viz., Chondrichthyes and Osteichthyes. The Chondrichthyes are represented by 131 species under 67 genera, 28 families and 10 Orders in the Indian region. The annual average landings of the Indian Chondrichthyes is 33,442 tonnes, of which, 15,537 tonnes come from the east coast and 17,605 tonnes come from the west coast and the rest come from the Andaman and Nicobar, and Lakshadeep Islands.
The Indian Osteichthyes are represented by 2,415 species belonging to 902 genera, 226 families and 30 orders, of which, five families, notably the family Parapsilorhynchidae are endemic to India. These small hillstream fishes include a single genus, viz., Parapsilorhynchus which contains 3 species. They occur in the Western Ghats, Satpura mountains and the Bailadila range in Madhya Pradesh only. Further, the fishes of the family Psilorhynchidae with the only genus Psilorhynchus are also endemic to the Indian region. Other fishes endemic to India include the genus Olytra and the species Horaichthys setnai belonging to the families Olyridae and Horaichthyidae respectively. The latter occur from the Gulf of Kutch to Trivandrum coast. The endemic fish families form 2.21 per cent of the total bony fish families of the Indian region. 223 endemic fish species are found in India, representing 8.75 per cent of the total fish species known from the Indian region and 128 monotypic genera of fishes found in India, representing 13.20 per cent of the genera of fishes known from the Indian region.
About 22000 species of fishes have been recorded in the world; of which, about 11% are found in Indian waters. Out of the 2200 species so far listed, 73 (3.32%) belong to the cold freshwater regime, 544 (24.73%) to the warm fresh waters domain, 143 (6.50%) to the brackish waters and 1440 (65.45%) to the marine ecosystem. Adequate protection of ecosystems is a necessary requirement for survival of all species and proper care is needed to overcome anthropogenic stresses . In the case of commercial species, rational exploitation is a pre- requisite for sustainability of the resources.
There are about 450 families of freshwater fishes globally. Roughly 40 are
represented in India (warm freshwater species). About 25 of these families
contain commercially important species. Number of endemic species in warm water
is about 544. Major warm water species are:
Bagarius bagarius, Catla catla, Channa marulius, C. punctatus, C. striatus, Cirrhinus mrigala, Clarias batrachus, Heteropneustes fossilis, Labeo bata, L. calbasu, L. rohita, Aorichthys seenghala, Notopterus chitala, N. notopterus, Pangasius pangasius, Rita rita, Wallago attu.
Cyprinids (family: Cyprinidae), Live fish (family: Anabantidae, Clariidae, Channidae, Heteropneustidae), Cat fish (family: Bagridae, Silurdae, Schilbeidae), Clupeids (family: Clupeidae), Mullets (family: Mugilidae), featherbacks (family: Notopteridae), Loaches (family: Cobitidae), Eels (family: Mastacembelidae), Glass fishes (family: Chandidae) and Gobies (family: Gobiidae) are the major groups of fresh water fishes found in India.
Cyprinidae is one of the largest families and is well represented in India with species ranging from few milimeters in length (minnows) to more than a metre (major carps). Among the Í 544 freshwater fish species in India, Cyprinidae accounts for nearly 24.12% of them.
Many of the Cyprinids, especially carps, are widely captured and form the mainstay of culture operations. Depending on their growth and utility in culture systems, the carps are grouped as the major carps (Catla catla, Cirrhinus mrigala, Labeo calbasu, Labeo rohita) and minor carps (L. fimbriatus, L. bata, C. cirrhosus, C. reba). A few exotic carps, as indicated below, have also been introduced into the country mainly for culture puroposes (Hypopthalmichthys molitrix, Ctenopharyngodon idella, Cyprinus carpio). The mahseers are also included in cyprinidae. Though many species of the genus Tor are found in the high altitude cold waters, some species like Tor khudree and Tor putitora occur in warmer waters. The genus Tor thus reveals a wide range of species diversity as regards adaptation to different ecological conditions. There is a serious decline of mahseer fishery in different ecosystems endangering its very existence, thus warranting adequate conservation of the fishes.