Triploid Grass Carp Production

Abstract

Abstract Triploid grass carp (Ctenopharyngodon idella) were produced by application of various cold or heat shocks to the eggs at different time intervals after addition of water to the milt-roe mixture and for varying durations. Up to 87% of grass carp produced were triploids. The optimum treatment was exposure of grass carp eggs, 1 min after mixture of milt and roe, to an instantaneous temperature increase of 12°C above ambient (26°C) for a duration of 3.5 min. Juvenile grass carp were graded into size-groups, and blood samples from 50-100 fish/group were analyzed with a Coulter counter and channelyzer to determine ploidy. Culling those size-groups with poor percentages of triploidy resulted in populations of up to 95% triploids being returned to ponds for further grow-out. Final selection of 100% triploid grass carp (which were to be stocked for aquatic vegetation management purposes) required analysis of each fish that was 150-250 mm total length.