| Popis: |
Intraspecific hybridization studies were carried out in three strains of Heterobranchus longifilis obtained from three ecological zones in Nigeria – rainforest; Onitsha strain, guinea savanna; Kainji strain and montanne vegetation; Jos strain with the aim of identifying the strains and improving the growth performance of the species. The highest percentage hatchability (93.86%) was recorded in the Onitsha strain and least in the Jos strain (61.60%). Among the intraspecific hybrids, the highest percentage hatchability of 96.09% was recorded in the hybrid cross of female Kainji and male Jos while the least was in the cross involving female Jos and male Onitsha. Maximum growth recorded in five weeks of outdoor rearing was 2.460 g in the Kainji strain and minimum was 1.984 g in the Onitsha strain. Among the hybrids, maximum growth was observed in the cross involving female Onitsha and male Kainji (3.000 g) and minimum of 1.822 g recorded for female Kainji and male Onitsha. There were no significant (P > 0.05) differences in the weight of the three parental strains and the six intraspecific hybrids at hatching and six weeks of rearing indoor aquaria and outdoor concrete tanks. The best survival value of 96% was recorded for the Jos strain followed by that of the hybrid cross involving female Jos and male Kainji. Key words: strain, intraspecific hybridization, hatchability, survival, growth. Journal of Aquatic Sciences Vol.17(1) 2002: 9-12 |
