Induced breeding and early growth of progeny from crosses between two African clariid fishes, Clarias gariepinus (Burchell) and Heterobranchus longifilis under hatchery conditions

Abstract

Objective: Hybridization of Clarias gariepinus (Cl) and Heterobranchus longifilis (Ht) and determination of their early growth parameters in the hatchery. Methodology and results: Four genetic crosses were made. These were (♀ × ♂): Cl X Cl, Ht X Cl, Cl X Ht and Ht X Ht. Triplicate batches of eggs from each cross were fertilized and incubated in 60L plastic aquaria with flow through water system using rubber type mosquito mesh netting as substrate. Variations in hatching rate and survival rates were not significantly different (P>0.05) for the crosses but fertilization rate in the cross Ht♀ X Cl♂ was statistically different from the other crosses (P<0.05, F-LSD). Specific growth rate (SGR) ranged from 11.43±0.502 (Cl♀ X Ht♂) to 13.70±0.167 in the Cl X Cl cross and these differed significantly from each other (P<0.05). In terms of growth, the pure breed Cl X Cl performed better than the other crosses, followed closely by the Ht♀ X Cl♂ cross which performed better than the other hybrid (Cl♀ X Ht♂). Conclusion and application of findings: Survival rates of larvae up to the first feeding stage are similar in all the genetic groups investigated. The pure Heterobranchus longifilis cross (Ht X Ht) gave the highest fertilization and hatching rate in comparison with the other genetic groups while pure breed Cl X Cl performed better than the other crosses in terms of growth. This implies that breeding exercises which involve pure catfishes should be employed more often to maximize fry production.