Embryonic development of diploid and triploid eggs of Clarias gariepinus (Burchell, 1822)

ABSTRACT

This study was conducted to evaluate the spawning performance and embryonic development of diploid and triploid eggs of the African Catfish, Clarias gariepinus. Triploidization was induced by heat shock at 41°C (for 20 min) at approximately 3 min after fertilization. Result obtained shows that the egg characteristics, fertilization percentage and the biometric parameters of hatched fry were similar in both treatments. However, more of the diploid eggs hatched (71.98%) than their triploid counterparts (56.31%). In addition, there were more observed abnormalities in the latter (35.43%) than the formal (2.71%). During the early embryogenetic cleavages stages (i.e. between two-cell and 64-cell stages), the diploid eggs advanced 5–23 min earlier than the triploid eggs. However, beyond the blastula stage, embryonic development was faster in the triploid; hence, hatching occurred 194 min earlier than the diploid eggs. The abnormal cleavages (unequal and asymmetric in nature) observed in the early stages of development in the triploids were thought to have resulted in the development of the somite at 50% epiboly. Consequently, abnormal hatched triploid fry from such eggs were short trunked. This study also affirmed the suitability of erythrocyte morphological as a simple and reliable index of discrimination between diploid and triploid African catfish.

KEYWORDS:

• African catfish
• heat shock
• abnormality
• embryogenesis

Acknowledgments

The authors are indebted to the School of Fisheries and Aquaculture Science, Universiti Malaysia Terengganu, Malaysia for providing broodstocks of C. gariepinus used in this study. We also acknowledge the help of some technical staffs of the PPSPA hatchery department during experimental trials of this study.

Disclosure statement

No potential conflict of interest was reported by the authors.