Induction of Triploidy in Clarias Gariepinus by Heat Shock of Fertilized Eggs

Abstract

Eggs and milt were collected from female and male Clarias gariepinus respectively. Fertilized eggs were given heat-shock at 40 and 41^oC for 4.5 minutes duration. The eggs were shocked at different post fertilization periods viz: immediately after fertilization, 2, 3, 4, 5 and 6 mins after fertilization. Percentage hatchability for 40^oC heat shock treatment gave 10, 14, 38, 42 and 68.7% for 2, 3, 4, 5 and 6 mins post fertilization periods respectively. While in 41^oC heat-shock treatment 14, 28 36, 52 and 41% were recorded for the 36%, 52 and 41% were recorded for the same post fertilization period. All eggs shocked immediately after fertilization at both 40 and 41^oC died. At 40^oC heat shock treatment, chromosome examination using 48 h old embryo gave 100, 80, 20 and 0% triploidy for 3, 4, 5 and 6 minutes post fertilization periods respectively. heat-shock treatment at 41^oC recorded 75, 100, 100 and 80% triploidy at 3, 4, 5 and 6 minutes post fertilization periods respectively. The fry of eggs shocked at 2 mins after fertilization died within 12 hours. Thus, chromosome examination was not carried out. The results of this work thus revealed that 100% triploidy could be successfully induced in C. gariepinus by heat-shock at 40^oC,sStarting 3 minutes after fertilization for 4.5 minutes.