Comparative Analysis of Spawn mass and Egg Regeneration in Clarias gariepinus and Heterobranchus bidorsalis for some size categories

Abstract

Understanding reproductive performance in aquaculture species is essential for optimizing hatchery success and improving yield. This study investigates the spawn mass and egg regeneration in Clarias gariepinus and Heterobranchus bidorsalis across four distinct size classes: < 1 kg, 1 kg, 1.5 kg, and 2 kg. Twenty-four healthy female fish (12 C. gariepinus and 12 H. longifilis) broodstocks were used. The fish were fed ad-libitum for initial 7 days before the first data collection and subsequent 90 days using commercial feed. Data obtained were compared between species using t-tests to determine statistical significance. The results shows that fish < 1 kg had no significant differences (p>0.05) in any measured parameters between the two species, suggesting similar reproductive output at smaller sizes. However, in the 1 kg and 1.5 kg categories, C. gariepinus consistently exhibited significantly higher egg weights than H. bidorsalis (p < 0.05), indicating superior spawn mass. This trend was most visible in the 1.5 kg group, where Clarias produced an average egg weight of 206.00 ± 11.53 g compared to 123.00 ± 20.22 g in Heterobranchus. Post-stripping weights also revealed notable differences, with Heterobranchus retaining more body mass after spawning in larger size classes. In fish > 2 kg, C. gariepinus maintained its advantage in egg production, with significantly higher egg weights (p < 0.05), while H. bidorsalis showed greater post-stripping body weight, suggesting a trade-off between reproductive investment and somatic maintenance. In conclusion, C. gariepinus demonstrates greater spawn mass and egg regeneration than H. bidorsalis, particularly in larger size categories, making it a more favourable and effective species for intensive aquaculture breeding programs.