Triploidy induced by heat shock in Oreochromis aureus. In：R.S. V. Pullin, J. Lazard, M. Legendre, J.B. A. Kothias and D. Pauly (eds.)

Abstract

Optimum conditions were sought for induction of triploidy by heat shock in tilapia, Oreochromis aureus. Triploids were identified using karyological techniques that detected metaphase chromosomes in the tail epithelial cells of larvae. Heat shock treatment at 41°C gave 100% triploidy when started at the zygotic age of 3 minutes and applied for 4 minutes. Higher percentages of triploidy were produced at higher water temperatures at short duration times in a range of heat shock treatments (40-43°C) applied for 2-8 minutes at the zygotic age of 3 minutes. No triploidy was induced when heat shock treatment was conducted at the zygotic age of 7 minutes or at a temperature of 39°C within a duration of 8 minutes. To produce 100°/0 triploidy in 0. aureus, heat shock treatment should be conducted at the zygotic age of 3 minutes, temperatures of 40 or 41°C. and with durations of 8 or 4 minutes, respectively.