Artificial spawning of Snow trout Schizothorax richardsonii (Gray)

Abstract

This fish has slow growth pattern and generally attains maturity in the third year. The adult fish, which inhabits in the snow-melt river, migrates to the tributaries receiving warm spring water for egg laying. The fish was observed to spawn at different elevations in different months of the year at a water temperature range of 18.0°C-21.5°C. In hill streams of Mandi and Bilaspur districts, the preferred temperature (18.0°C - 21.5C) prevailed during March when the fish was observed to spawn. In the streams of Chamba, Mahasu and Kinna ur districts, Spawning was observed in May and June, while in the streams of Kangra Valley, which are at a lower altitude, spawning take place in October–November. In Kumaon region of Uttarakhand, fish breeds during September-October. Fish spawn naturally in clear water on gravelly/stony grounds or on fine pebbles at 1-3 m depth. Water current of 2.8-4 m/sec, pH 7.5, dissolved oxygen concentrations of 10-15 mg/L, and gravel size of 50-80 mm are the optimal conditions for spawning. Schizothorax richardsonii has a total fecundity to a tune of 20,000-25,000 per kg body weight.Water temperature of 15-20°C might be the optimum temperature for eggs incubation as it takes about 11 days for hatching. They attach eggs to the substrate. The size of eggs is also quite large (3.7-4.0 mm) Compared to allied Schizothoracine Species and vitalline membrane of the egg is completely filled with the yolk. This is probably in severe cold Season to meet food requirement of embryo and yolk sac fry. It has a 'synchronism' type of maturation and during the breeding season, males develop 'nauptial tubercles' on the snout. Fry stay on sand and gravel at bottom.