Optimisation of UV treatment duration to induce haploid androgenesis in the Nile tilapia (Oreochromis niloticus L.)

The optimum UV duration times of eggs were examined in order to develop a simple and safe method for inducing androgenetic development in the Nile tilapia, Oreochromis niloticus. The yield of androgenetic haploid O. niloticus to the pigmentation stage was 18.53 +/- 5.3% (relative to controls) with an optimal UV irradiation dose of 540 Jm(-2) (at 150 muWcm(-2)) for 6 min. Most embryos developing after fertilisation with normal spermatozoa showed abnormal morphology and a haploid number of chromosomes (n = 22). The success of oocyte denucleation was also assessed by using the recessive "blond" skin pigmentation character.