Monosex female production in the silver barb (Puntius gonionotus Bleeker).
Gynogenetic female silver barbs (Puntius gonionotus) were reared on artificial plankton containing 25-150 mg 17α-methyltestosterone (MT)/kg for 3-5 weeks starting 1-3 weeks after hatching. The highest percentages of males (33.9 and 29.8% males respectively) were found after treatment with 25 mg MT/kg for 4 or 5 weeks, starting at 2 weeks post-hatch. The majority of crosses between such males and ordinary females gave all-female progeny, which supports the hypothesis of female homogamety and establishes that large-scale production of monosex females is feasible in this species. A growth trial comparing monosex female groups with mixed-sex groups in pond culture showed an increase in total pond yield by 28.7% at 5 months and 22.9% at 7 months for the all female groups.