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Abstract

The eastern Himalayan region, hot spot for fish biodiversity, is characterized by extreme climate and low water temperature. The poor somatic growth and delayed gonadal maturation in carp due to low temperature add considerably to the expense of producing fish from aquaculture. This study examines the response (somatic growth and gonadal maturation) of three carp species (Hypopthalmichthys molitrix, Cirrhinus mrigala and Labeo bata) to low and elevated water temperature. The effectiveness of the water temperature on fishes was assessed by weight gain, gonadal index (GSI), histology, and germ cell count. This study revealed a significant increase in body weight and gonadal index in all the three species from warm water at the end of one year culture period. Further, at the end of 12 months culture period, males from all the three species from greenhouse pond appeared to have prominent cysts of spermatogonia and other active spermatogenic stages and females have large cysts of oogonia interspread with oocytes at various stages of follicular development, a condition not observed in any fish species from the low water temperature. These results suggesting that elevation in water temperature, greenhouse as in this case, in fish ponds of eastern Himalayan region could tremendously benefit the aquaculture in terms of growth enhancement and brood stock development in considerably short period.