Artificial Induction of Ovulation in Pondraised Mahseer, Tor khudree Using Carp Pituitary and Ovaprim

Abstract

A total of 102 induced breeding trials were carried out at Harangi, Karnataka between 1993 and 1997, with a view to standardize hatchery technology for pond-raised mahseer, Tor khudree. The initial seeds for raising the broodstock were brought from Lonavla, Maharashtra in 1990 and reared in mud-bottomed masonry ponds. Male and female brood fish were maintained separately and fed on improved diets. Female brood were injected with HCG at 5 mg•kg-1 once a month from December till the onset of monsoon in June, to improve fecundity. In all the trials, observations on water temperature, response of females to inducing agent, weight of females that responded, fecundity, time required for ovulation and fertilization rate were recorded. The following are the findings from the series of breeding trials conducted with different objectives. Between the two inducing agents evaluated, Ovaprim performed better in terms of response of female (40%), than pituitary extract (29.63%). Feeding broodstock with a diet having 24.5% crude protein resulted in higher ovulation response, shorter time for ovulation and higher fertilization rate of eggs, compared to 31.5% crude protein diet. Plankton weight recorded in ponds fed on low protein was less than in ponds receiving high protein diet, indicating better utilization of natural food in the former. Cryopreserved spermatozoa performed comparably (P>0.05) with that of normal spermatozoa in terms of fertilization rate and quality of hatchlings. The duration of egg hatching and yolk absorption were found to be temperature dependent. Fertilized eggs incubated in Mangalore at 27-28o C took 60 hours for hatching and 95 hours for yolk sac absorption, compared to 120 hours taken for hatching and 238 hours for yolk absorption by those maintained at 20-24o C in Harangi.