Effects Of Latency Period On Relative Fecundity, Egg Fertility, Egg Hatchability And Fry Survival Rate Of Heterobranchus Longifilis (Val. 1840)

ABSTRACT

Bloodstock of Heterobranchus longIlis (Val. 1840) were obtained acclimatized and phypophysed with ovaprim (an ovulating agent). Eggs were stripped from the female breeders after hypophysation while milt obtained from the male breeders by dissection. Proliferation and ease of flow of eggs were observed as the latency periods increased. Lowest mean value of 32,750 eggs was obtained at the 8th h while highest mean value of 97, 000 eggs was obtained at the 17th h of latency period. Latency periods had a positive relationship with the relative fecundity, (r2 0.969). In the case of the hatchability, there was no regular pattern observed in the values. At the 1 i" h the highest peak value obtained was 61.71% while at the l? h the value of 57% was obtained. Hatchability had a weak relationship with latency periods (r2= 0.204). Highest peak value of 61.94% was obtained at the 1 h and lowest value of 25% was obtained at the 1 71ti h for fry survival rates. Latency periods and fry survival rates were found to be adversely related (r2= 0.968). All the fry that survived within each of the various groups were not of equal sizes.