Characteristics of diploid and triploid hybrids derived from female Megalobrama amblycephala Yih × male Xenocypris davidi Bleeker

DNA content, chromosomal number, morphological characters, aquaculture performance, and gonad development of Megalobrama amblycephala Yih (BSB) (♀) × Xenocypris davidi Bleeker (YT) (♂) hybrids were analyzed. Diploid hybrids with 48 chromosomes (2nBY, 2n = 48) and triploid hybrids with 72 chromosomes (3nBY, 3n = 72) were found in the hybrid progeny, accounting for 88% and 12%, respectively. The two kinds of hybrids exhibited phenotypic divergence and hybrid heterosis from BSB and YF. Hybrids were identified by the number of anal fin rays present. Body height of the two hybrids, especially that of 3nBY, was significantly greater than that of YT (P < 0.05). In addition, the hybrids showed significantly higher growth rate compared to their parents, and higher flesh rate compared to BSB (P < 0.05). Neither hybrid could produce mature eggs or sperm at 2 years old. Histological observation revealed that gonad development of the hybrids was not synchronous and exhibited abundant polymorphism. This study has produced a new variety of fish with potential benefits to aquaculture. It also provides new insights into the genotypic and phenotypic diversity of hybrid fish from distant hybridization between subfamilies.

► We conducted the inter-subfamily hybridization of two fish species.
► Diploids (2n = 48) and triploids (3n = 72), were found in offspring.
► The diploids account for 88.2% of the hybrids, much more than 11.8% triploids.
► The hybrids exhibit improved aquaculture performance.
► Gonadal development of the hybrids exhibited abundant polymorphism.