Reproductive biology and artificial propagation of chocolate mahseer Neolissocheilus hexagonolepis (Mc Clelland) in Meghalaya, India

Abstract

The chocolate mahseer Neolissocheilus hexagonolepis (Mc Clelland) is a commercially important species of mahseer group which needs immediate attention due to its reduced abundance in Meghalaya. This fish is widely recognized as a sport fish by the anglers, as ornamental fish by the hobbyists and also a priced food fish. Fishes were found to mature from May onwards and gravid fishes were available in rivers from July to September. Females were larger in size when compared to males in the same age group. The sex ratio observed was 1 female: 1.26 male. Attainment of first maturity occurred when males were 9+ months and females were 11+ months old. The minimal length and weight at first maturity of female fishes were 17.8 cm and 70 g respectively whereas males attained maturity at an average length of 17.3 cm and weight of 50 g. The Gonado-somatic Index in ripe female was 16.19 and the average fecundity factor was 70.18. The fish was bred successfully in captive condition through stripping. Fertilization percentage of eggs ranged from 80 to 85. Incubation period varied between 81-97h and the percentage of hatching was 75-80. Yolk-sac absorption in larvae was complete in 6+ days after hatching. The spawn was stocked in glass aquaria and on an average, 85% survival was recorded after 15 days of rearing when they attained an average length of 2.084 cm and weight of 0.195 g. The fry was subsequently reared in cement cisterns @ 1 no. per litre and on an average, 92% survival was recorded after 60 days of rearing. During this period, the fish attained an average length of 4.82 cm and weight of 0.856 g.