Cold water fisheries:

The cold water fishes adopted to live below 100C to 200C temperature. The upland water at high altitudes of mountains and the spring water at low altitude in temperate regions remain cooler than the rest and the cold water fishes flourish in these region. Such water bodies comprising several hill streams, rapids, pools, lakes and reservoirs are abundantly found in the Himalayan region and in the Deccan plateau region of peninsular India. These are either fed by melting snow and the springs as in north or by the rain water as in Deccan plateau.

During recent years, there has been growing realization for development of cold water fisheries in India, since the production from cold water is neglisable in comparison to total inland catch. The trout hatchery established in Kashmir is one of the potential sources from where the brown trout have been transplanted to the upland waters of Jammu, Kashmir, Kullu, Simla, Kangra, Nainital, Shilong and Arunachal. Other hatcheries constructed at Nilgiris and Kerala.

Indigenous cold water fishes:

Mahaseer, Snow trout and Indian hill trout are the principle cold water fish species inhabiting the mountain waters of India.  Mahaseer fishery of cold water: It is one of the major game fishes of Himalayas. How ever, it has not received attention as exotic fishes in India. It is generally found in large sizes and abundant in quantities from mountain streams and rivers. Some of the important species of mahaseer are:

1) Tor tor (Hamilton): It is characterized by head shorter than the depth of the body. It attains a length of 1.5 m and occurs along the foot hills of Himalayas from Kashmir to Assam and in the river Narmada and Tapti. It is insectivorous in its juvenile stage but becomes herbivorous when adult. It has a prolonged breeding season from July to December. The eggs are laid in batches. It constitutes the major fisheries of rivers Narmada and Tapti.

2) Tor putitora (Hamilton): It is commonly called as golden or common Himalayan Mahaseer. It has head longer than the depth of the body. It occurs in Himalayas from Kashmir to Darjeeling hills. This fish breeds thrice in a year, firstly during winter months (January to February), subsequently in summer (May –June ) and lastly in August – September.

3) Tor mosal (Sykes): Mosal Mahaseer has head more or less equal to the depth of the body. It is found in the Mountain Rivers on foot hills of Himalayas, Kashmir, Assam and Sikkim.

4) Tor mosal mahanadicus: It resembles the mosal mahaseer in all aspects except, it is found in the river Mahanadi and that its head having small eyes is often higher than the depth of the body.

5) Tor khudree (Sykes): It is characterized by its head being as long as the depth of the body. It is found in Orissa and throughout peninsular India. It attains a length of about 1.3 m.

6) Acrossocheilus hexagonolepis (Mc Clelland): It is commonly known as copper or chocolate Mahaseer. It has an oblong andm compressed body with an obtusely rounded and prominent mouth. The colour of the body is deep bluish grey with darkish fins. These are mainly distributed Upper Ondia,Assam and Cauvery river inTamil Nadu. It attains a length over 60 cm. It differs from Tort or in having hexagonal shape of its scales and the thin lips.

7) Snow trouts: Snow trouts are chiefly represented by two genera, namely Scizothorax and Schizothoraicthys.

Schizothoraichthys: It is represented by three species in Himalayas viz. S. richadsonii, S. Plagistomus and S. molesworthi. These are found in snow fed streams of Assam, estern Himalayas, Sikkim, Nepal, Kashmir. The genera is represented by S. esocinus, S. progastus and S. kumaonensis, of these, the S. esocinus is found in Kashmir and Ladhak, S. progastus in the hill streams of Ganges at Hardwar and Darjeeling and S. kumaoneus in Nainital.
The Indian hill trout: Berilius is known as Indian hill trout. It is represented by four species, namely B. bendelisis, B. bola, B. vagra and B.gatensis.

Exotic cold water fishes:

The exotic fishes found in the hill streams of India chiefly include the trouts, mirror carps, crucian carps and tenches.

1. Trouts: Exotic trouts in India are represented by three species, two of them belonging to genera Salmo and one to Onchorhynchus.

(a). Salmo gairdneri gairdneri – It is commonly known as rainbow trout or steel head it is a native of North American Pacific water and was imported to India in1907. Presently, these are one of the most successful trouts of Indian waters for cultural purpose because these adapt easily in comparison to the brown trout’s. Moreover, they promptly feed on artificial food and can withstand the high temperature and O2 depleted water as well. Their incubation period is shorter and the rate of development and growth is faster. Upon being well fed, they attain a length of 400-500 mm in three years and weight about 5.5 kg. The body is elongate head short and mouth comparatively small. The color of the body is variable, depending on sex and environment. It is chiefly a river fish but is cultivated in confined water as well .It does not breed in ponds but artificial fertilization is possible. The fry feed mainly on planktons but half grown and adults are carnivorous. It is a game fish too.

(b). Salmo trutta fario – It is commonly called as brown trout. It is a native of the mountains water of central and Western Europe. This fish was the first one reproduced and reared artificially in India. Although it was introduced to mountain waters of all hills, it could establish itself only in the streams and farms at Kashmir and in river beas in Punjab. It feeds upon the crustaceans and large living prey at the bottom. It attains a maximum length about 46.5 cm, depending upon the natural food availability. During breeding seasons, the fish swims up streams to spawn on gravel bedded shallows of fast current water.