Genetic Improvement of Three Strains of Heterobranchus longifilis (Valenciennes, 1840) for Enhanced Food Security and Poverty Alleviation in Nigeria.

This study was designed for genetic improvement of African Catfish, Heterobranchus longifilis, for enhanced food security and poverty alleviation in Nigeria, through intraspecific hybridization of germplasm from three eco-regions of Nigeria. Sexually mature species of the fish were collected from the wild; Guinea Savanna (Benue River, Makurdi, MK), Rainforest (Niger River, Onitsha, ON) and Sahel Savanna (Rima River, Sokoto,SK). Sex ratio of female to male was 2:1. They were transported to the Coordinating Institution, College of Education, Oju, and acclimatized in earthen ponds for 14 days. Nine mating combinations were attempted in a bid to improve the performance of the progenies. Growth and survival were then monitored for two and a half months (75 days). The progenies of the various mating combinations were further reared in earthen ponds to sexual maturity for a period of nine months (270 days). During this period, their weights and gonads were 
examined monthly, and in order to determine the true commercial application of the intraspecific crosses, growth performance was evaluated based on mean weight gain, mean final weight and specific growth rate. The hatchlings of the various mating combinations were initially reared indoors for two weeks and later transferred outdoors for 56 days during which length and weight data were collected. Of the nine mating combinations in this study, the highest percentage hatchability was recorded in the pure line crosses; Sokoto, Makurdi and Onitsha strains (85%) while the least was recorded for the intraspecific cross between female Onitsha and male Makurdi (♀ON x ♂ MK:63%). However, the intraspecific hybrids had higher survival rates than pure line hybrids. Growth performance of fry of the various mating combinations reared indoors for two weeks showed that the growth rates of the cross breeds were significantly higher than the pure breeds. The cross breed ♀MK x ♂ON had the highest weight gain (0.88 ± 0.00g) while ♂SK x ♂SK had the least weight gain (0.56 ±  0.00g). The growth parameters of the progenies reared outdoors in hapas for 56 days showed that the cross breed ♀MK x ♂SK had the highest mean final 
weight (1.560± 0.06g), mean weight gain of 1.450 ± 0.06g and specific growth rate of 0.047 ± 0.00g. At sexual maturity, all the cross breeds had higher mean final weights than their corresponding pure breeds; ♀MK x ♂SK(700g), ♀MK x ♂ON(653g) and ♀MK x ♂MK(615g), 
♀ON x ♂ SK(655g), ♀ON x ♂ MK(605g) and ♀ON x ♂ ON(571g), ♀SK x ♂MK(605g), ♀SK x ♂ ON(553g) and ♀SK x ♂SK(501g). Based on the findings of this research, it can be concluded that improving performance of fish population through intraspecific crosses of fish strains from 
different eco-regions is possible. It is therefore recommended, amongst others, that there is a need to produce the F2 and F3 generations, and even go further to add selection yield in genetic gains. Also, there is a need to do a comparative study of growth performance of fish raised out in hapas, concrete tanks and earthen ponds.