STUDIES ON CERTAIN ASPECTS OF THE REPRODUCTIVE BIOLOGY OF

Certain aspects of the reproductive biology of O. mossambicus (Peters) from a domestic pond of Assam have been described. Morpho-histological studies of the gonad revealed the existence of six maturity stages in O. mossambicus while gonadosomatic index (GSR) indicated that the breeding season extended from March to October. The frequency four polygon of ova diameter showed peaks suggesting four times of spawning of the species in this part of the country. Appearance of first sexual maturity was observed in 5 – 10cm length groups in female and 10 – 15cm in male specimen. Fifty per cent of male mature by the time they attained an average length of 12.5cm and this occurring at 7.5cm in females. Absolute fecundity ranged from 100 to 850 while the relative fecundity varied between 6 and 16. There was positive correlation (r = 0.88) between GSR and Condition factor (K) and negative correlation (r=- 0.84) between GSR and gonadosomatic index (GSI). Fecundity was highly correlated with total length (r = 0.99), body weight (r = 0.85) and ovary weight (r=0.62) of the fish