Abstract

A study was conducted to induce triploidy in African mud catfish Clarias gariepinususing cold shock. The fertilized eggs were exposed at one temperature regime of0^°C with varied shock treatments of 0, 15, 25 and 30 min. Some 3 min after fertilization, the success of triploidy was determined by the presence or absence of bent trunk in the fry as reported by (Aluko et al., 1997). The shock duration of 25 min at 0^°C gave the best result of 55% hatch with survival at the end of the exposure regime of 43.5%. Shock exposure of 30 min gave 30% hatch while 15 and 20 min exposure were poor at 15% hatch.

Key words: Clarias gariepinus, cold skock regime, triploidy, hatchability.