Abstract

Olufeagba S. O. and Yisa Moses

Chromosome engineering is a biotechnology tool currently used for fish improvement. Heterobranchus longifilis gynogens were produced by fertilizing eggs with irradiated sperm of the same species and subjecting the zygote to cold shock at 5°C, 40 min after fertilization for 15 min. To induce androgens, irradiated eggs were fertilized with normal spermatocytes and allowed to incubate for 40 min, then cold-shocked at 5°C for 15 min in a thermoregulated chamber to restore diploidy. Induction of gynogenesis and androgenesis was possible as 50.7 and 6.7% hatchability were obtained, respectively. After six days of rearing, the percentage survival of gynogens (97.8%) was better than that of the androgens (6.25%).