Evaluation of Hybridization in Two African Catfishes (Siluriformes, Clariidae): Exotic (Clarias gariepinus Burchell, 1822) and Native (Clarias jaensis Boulenger, 1909) Species under Controlled Hatchery Conditions in Cameroon

The study was conducted to evaluate reciprocal hybridizations in the African catfishes Clarias gariepinus and Clarias jaensis using artificial reproduction under controlled hatchery conditions. The results revealed that the highest fertilization (82.77%) and hatching (67.77%) rates were achieved in the hybrid cross female C. jaensis x male C. gariepinus (Fcj x Mcg). Deformed larvae rates ranged from 9.01 to 16.33%; the hybrid Fcj x Mcg recorded the lowest rate. Survival rates in the larval stage were higher than 80% whatever crossing considered. However, it was higher in the hybrid Fcj x Mcg unlike its homologous female C. gariepinus x male C. jaensis (Fcg x Mcj) which recorded the lowest value (81.70%). In the fry stages D32, survival rates were low than 65%. They were higher and comparable in parental cross Fcg x Mcg (57%) and hybrid cross Fcj x Mcg (61.67%). The lowest survival rate (41.16%) was recorded in parental cross Fcj x Mcj. The hybrid cross Fcj x Mcg expressed the highest growth performances close to those of parental cross Fcg x Mcg, unlike parental cross Fcj x Mcj. Size heterogeneity was greater in hybrids. In all crosses, the condition factor K was low (0.58 to 0.85%), the length-weight relationship was significant with determination coefficient R-2 greater than 0.9. The growth was of the negative allometric type (with b less than 3). Positive heterosis has been recorded for both survival and growth at all stages of development. It was concluded that C. jaensis x C. gariepinus hybridizations are indeed possible and would contribute to improve Clarias fry production in captivity. However, the pure strains of Clariidae remain endangered in the natural environment.