An improved hybrid bream derived from a hybrid lineage of Megalobrama amblycephala (♀)×Culter alburnus (♂).

Distant hybridization is an important technique in fish genetic breeding. In this study, based on the establishment of an allodiploid fish lineage (BT, 2n=48, F1–F6) derived from distant hybridization between female Megalobrama amblycephala (BSB, 2n=48) and male Culter alburnus (TC, 2n=48), and the backcross progeny (BTB, 2n=48) derived by backcrossing female F1 of BT to male BSB, an improved hybrid bream (BTBB, 2n=48) was obtained by backcrossing BTB (♀) to BSB (♂). Moreover, the morphological and genetic characteristics of BTBB individuals were investigated; BTBB was similar to BSB in appearance but had a higher body height than BSB. The study results regarding chromosome numbers and DNA content indicated that BTBB is a diploid hybrid fish. The 5S rDNA and Hox gene of BTBB were inherited from the original parents. Gonadal development in BTBB was normal. On the other hand, BTBB had a faster growth rate, higher muscle protein level, and lower muscle carbohydrate level than BSB. Hence, bisexual fertile BTBB is promoted and can be applied as a high-quality fish, and it can also be used as a new fish germplasm resource to develop high-quality fish further. Thus, this study is of great significance for fish genetic breeding.