Comparative ovulation in clariidae using crude HCG from early pregnancy urine
Members of Clariidae do not spawn in captivity. Culture of these species in captivity must necessitate induced spawning of the eggs. Synthetic hormones have been known to assist this process. This paper used purified crude HCG from early pregnancy urine to assay ovulation in three species of Clariidae. Purification and extraction of crude HCG was carried out by the techniques involving alcohol precipitation, ion exchange chromatography and gel filtration. Biological activity of the purified homogenate was tested on three species of clarridae: Heterotranchus longifilis, clarias gariepinus and clarias anguillaris at a dose 2.5i.u/gram body weight. Eggs were stripped from fish after a latency period of 12-20hours. H. longifilis gave the highest number (percentage) of stripped eggs and showed significant difference with clutch size (PLO.05) when compared with C. gariepinus and C. anguillaris. No significant difference (P > 0.05) was observed in fecundity between the two Clarias species. However all the three species showed high fecundity when treated with the homogenate. The results show positive implications for the culture of the species in captivity.