The Formation of a Novel Intergeneric Hybrid Fish Derived from Megalobrama amblycephala (♀) × Culter dabryi (♂)

Distant hybridization in fish serves to integrate the genetic material from two distinct, distantly related species. In this study, we successfully produced a new hybrid fish (BG) through the intergeneric hybridization of blunt snout bream (Megalobrama amblycephala, BSB, 2n = 48, ♀) and green tip culter (Culter dabryi, GTC, 2n = 48, ♂). The objective of this research was to characterize the genetic, morphological, reproductive, and nutritional features of the hybrid compared with its parents. The DNA content and chromosomal number analysis revealed that BG was a diploid hybrid fish with 48 chromosomes. Integrated analysis of 5S rDNA, mitochondrial DNA, and Sox9 gene sequences revealed that BG predominantly inherited its genetic traits from BSB. Notably, certain gene fragments (376 bp segment of 5S rDNA class II and 718 bp segment of BG Sox9-II) originated from the paternal GTC, demonstrating biparental genomic integration. The growth performance analysis revealed that BG exhibited enhanced growth, achieving a body weight significantly greater than that of BSB and 1.81-fold that of GTC (both p < 0.05). The reproductive analysis indicated that BG possessed bisexual fertility, with testicular histology revealing accelerated spermatogenesis relative to BSB. Additionally, the nutritional analysis of BG muscle revealed elevated levels of crude protein (18.13%) and umami amino acids (5.45%) compared to those in its parents. BG showed higher growth, bisexual fertility, and improved muscle nutritional composition. This hybrid represents a promising resource for cyprinid breeding and aquaculture diversification.