Observations on larval development of chocolate mahseer Neolissochilus hexagonolepis (McClelland, 1839)

Abstract

Present study embodied larval development of chocolate mahseer, Neolissochilus hexagonolepis in controlled conditions in the laboratory, from hatching till complete absorption of the yolk sac. Details pertaining to larval development of chocolate mahseers are not available, but are of obvious benefit for a better understanding of life history and for captive seed production and hatchery management programmes for aquaculture as well as for conservation purposes. The mature eggs and sperms were fertilized by dry stripping method. The fertilized eggs were then incubated in a flow through hatchery. The fertilized eggs were transparent, demersal, spherical, non-adhesive and brownish in colour with a diameter of 2.8 to 3.1 mm. Hatching started 40 h post-fertilization and was completed within 22 h at of 22 ± 2 0C. Newly hatched larvae measured 8.5 mm in length and were devoid of mouth and pigmentation. The yolk sac was completely absorbed within 16 days post-hatching on attainment of 14.32 ±0.26 mm total length. At the same time the digestive system became fully developed and larvae started taking exogenous feed. The findings of the present study provide valuable information that may help establishing large scale seed production technique for chocolate mahseer.