he mahseer or golden mahseer (Tor putitora, Hamilton) is considered king of the Himalayan fishes. It is an important edible fish in the rivers and tributaries of Nepal (Shrestha, 1997). The mahseer’s range extends throughout southern Asia, from Iran in the west to Thailand in the east, and from Sri Lanka in the south to the Himalayas in the north. This species resembles a typical carp in structure and appearance. The body is semi-round and slightly flattened along the ventral surface from near the mouth opening to the anus, and there is sudden tapering of the body just after the anal region. Eyes are large, round, and situated more towards the dorsal surface. The nostrils are located near the eyes on either side of the mid-dorsal line. The head is provided with two pairs of feelers—the rostral and maxillary barbells. The entire body, except the head and fin, is covered with large-sized cycloid scales and the fish, therefore, is called “large-scale barbel.”
It is one of the largest species of the Cyprinidae family, attaining a length up to 5 feet, and sometimes exceeding 70 pounds. In India, the mahseer affords the same kind of sport as salmon in the British Isles, and it rivals that fish in size, strength, and activity. Its flesh is likewise much esteemed.
The mahseer is oviparous and the sexes are separate. During spawning season males develop strong tubercles and hence are easily distinguished from the female ones. Its reproductive system consists of gonads, in which the germ cells are formed, and the gonadial ducts, through which the germ cells leave the body.
The mahseer is generally found in cold, well-oxygenated rivers, with rocky gravel beds. However, during winter months the fish moves into warmer waters due to its migratory habits. Mahseer live and grow to maturity in larger rivers and migrate to headwater creeks to spawn from June to September. As soon as spawning is over, they move downstream to feeding areas of larger rivers where they grow older and larger every year and continue to spawn.
The months from August to September are the breeding periods for mahseer in the Himalayas. In these months, water flow, temperature, pH, and dissolved oxygen are favorable for breeding. Mahseer produce 45,800 to 75,500 eggs. A fertilized egg measures 2.18 to 2.87 mm. They grow well in highly mineralized water with high specific conductance and nearly neutral pH.
They are long-lived, slow growing, and feed on insects and fish fry of other species. Mahseers feed mainly on drifting aquatic and terrestrial insects. As they grow, they become increasingly piscivorous. In the creeks, mahseers feed on fish and shrimps. Male fish mature when two years old and about 200 mm total length. The female matures at 300 mm total length after about three years (Shrestha, 1994).
This versatile fish is ranges from just above sea level to 2,000 meters above. In 1987, the Mekong River in southeast Asia was restocked with Indian mahseer to provide food for local communities. However, pond culture of mahseer was not successful due primarily to the slow growth of the fish in captivity. Islam (2002) concluded that the fish is not suitable for monoculture due to extremely high FCR (5–7).
However, water temperature remained high (over 28°C) throughout their experimental trial, which might have caused slow growth of the fish, and thus there remains the possibility of the species performing better in lower water temperatures. Threats that mahseer natural stock is facing include dams, deforestation, soil erosion, and illegal fishing. Hence, development of an efficient cage culture system can help maintain fish species diversity in the region and also a constant supply of this highly esteemed fish to the consumer.
Literature cited
Islam, S.M., 2002. Evaluation of supplementary feeds for semi-intensive pond culture of mahseer, Tor putitora (Hamilton). Aquaculture, 212: 263–276.
Shrestha, T.K., 1994. Migration and spawning of golden mahseer in Himalayan waters of Nepal. J. Freshwater Biol. India, 6(1): 71–77.
Shrestha, T.K., 1997. The mahseer: in the river of Nepal disrupted by dams and ranching strategies. Department of Zoology, Tribhuvan University, Kathmandu, Nepal, 259 pp.
