Abstract
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 × male C. gariepinus (Fcj × Mcg). Deformed larvae rates ranged from 9.01 to 16.33%; the hybrid Fcj × 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 × Mcg unlike its homologous female C. gariepinus × male C. jaensis (Fcg × 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 × Mcg (57%) and hybrid cross Fcj × Mcg (61.67%). The lowest survival rate (41.16%) was recorded in parental cross Fcj × Mcj. The hybrid cross Fcj × Mcg expressed the highest growth performances close to those of parental cross Fcg × Mcg, unlike parental cross Fcj × 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 R2 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 × 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.
Highlights
Despite the consequences of “introductions” on native species [8], the Mbo Floodplain has become over the years an “attic“ of catfish juveniles for the stocking of fish ponds in Cameroon since the introduction of this species; to the point where its endogenous sister C. jaensis would be in the process of disappearing in the catches
If this hybridization is possible in the natural environment between the two species, it may eventually lead to the total disappearance of the two purebred Clariidae, especially if their hybrids are interbreeding [7]. e question that arises is whether the abundance of juveniles recorded in the Mbo Floodplain since the introduction of C. gariepinus should be due to the hybridizations between the two sister fish species?
Fertilization rates were comparable to those generally observed in Clariidae under controlled conditions: 80 to 95% in C. gariepinus [20], 87.1 to 95.2% in H. longifilis [21], and 79.25 to 87.57% in C. jaensis [13]
Summary
Hybridization is the mating of genetically differentiated individuals or groups and may involve crossbreeding within a species ( known as line crossing or strain crossing) or crosses between separate species [1]. is breeding technique is used by aquaculturists in the hope of producing aquatic organisms with specific desirable traits or general improvement in performance [1]. ere are three types of hybridization in aquaculture: intraspecific, interspecific, and intergeneric hybridizations.Interspecific hybridization has been practiced for a long time in a variety of fish species to increase growth performance, produce sterile animals, improve fleshAdvances in Agriculture quality, increase disease resistance, improve environmental tolerance, and manipulate sex ratios, as well as various other traits (overall improvement, hybrid polyploidization, experimental hybridization, and unplanned or accidental hybridization) to make fish more profitable to raise [1,2].e African catfish Clarias gariepinus is an exotic species in Cameroon, where it is established in many rivers [3,4]. Is species was accidentally introduced into the Mbo Floodplain by escaping from the fish ponds located upstream of the University of Dschang [4] In this plain, she cohabits with her sister Clarias jaensis, an indigenous catfish of Cameroon, and was the most abundant alien species [6]. Despite the consequences of “introductions” on native species [8], the Mbo Floodplain has become over the years an “attic“ of catfish juveniles for the stocking of fish ponds in Cameroon since the introduction of this species; to the point where its endogenous sister C. jaensis would be in the process of disappearing in the catches. E first successful artificial breeding of this species in captivity reported very low hatching rates (
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