Hybridization and Growth Performance of Progeny from Crosses between Clarias gariepinus and Heterobranchus sp.

Mixed hybridisation trials involving Clarias gariepinus (CG), Heterobranchus longifilis (HL), and Heterobranchus bidorsalis (HB) were carried out with success using Ovulin as inducing agent. The crossing was followed by an early growth trial using post-yolk sac larvae that lasted ten days. Latency periods in the two catfishes differ, with 11 hours in crosses involving female CG and 12 hours in crosses involving female HL. The fertilisation rates of eggs from the females of the two species indicate that there is no significant discernment in fertilisation (p>0.05), with values ranging from 68.38% (CG×HB) to 80.94% (HL×CG). However, rates <80% indicate egg quality problems. The hatching rate was significantly higher (p<0.05) in both C. gariepinus (62.12%) and Heterobranchus sp. (47.75%) line crosses than the hybrids. There is an additive genetic effect due to the combination of pure-line male and female gametes that elicit better growth as against survival in crosses involving C. gariepinus. The genotype for better survival is in the maternal line of H. longifilis. These culminate into heterosis for growth in hybrid CG×HB and survival in hybrid HL×CG.