Studies on the genetic improvement of the African catfish (Clarias gariepinus burchell, 1822) by triploidy

Abstract

This study sought to assess the possibility of genetically improving the performance of the African catfish using triploidy techniques. The experiment was carried out using Completely Randomized Design (CRD) with varied temperatures, time spent before shock after fertilisation, and durations of the shock for the triploid production experiment and four treatments replicated thrice for the culture experiment. Fertilised eggs from each female parent stock were subjected to either cold or heat shock treatments. The result showed a significant (p<0.05) increase in the hatching time and survival of the fertilized eggs subjected to different cold and heat shock treatments as compared to the control which recorded the shortest hatching time of 22.48 ± 0.00 hours. The temperature regime of 2^oC recorded the highest approximate yield of triploids (98.33 ± 1.66%), while the prolonged duration of the shock of 30 minutes at the temperature regime of 3^oC significantly increased (p<0.05) triploid yield. Comparatively, triploids significantly gained more weight, had an increased growth rate, and grew longer than the diploid counterparts with an average of 11.22 ± 1.07 g, 0.013 ± 0.001%, and 21.49 ± 0.47 cm respectively. The highest comparative cost of the diet of 1000 catfish juveniles occurred in triploids with a stocking density of 7 fishes/m² (N14,132.50). However, the seed, feed, and variable costs consistently decreased with increasing stocking densities across the ploidies. It is therefore concluded that the triploids were superior in both production attributes and cost benefits.