Induction of heterozygous and homozygous diploid gynogenesis in Betta splendens (Regan) using hydrostatic pressure

Optimum conditions for hydrostatic pressure treatment for duplication of chromosome set in gynogenetically activated fighting fish, Betta splendens (Regan), eggs were identified. Maximum survival of heterozygous gynogens was 50%, when 2.5-min-old eggs, after insemination with UV irradiated tilapia sperm, were pressure shocked at 7000 psi for 6 min. The frequency (21%) of homozygous gynogenetic fry was high, when the 34 min (post-insemination) old eggs, which were inseminated with tilapia sperm, were pressure shocked for 5 min. Sex ratio of gynogenetic progeny suggested that the mechanism of sex determination in this fish is homogametic female and heterogametic male.