Transcriptomic and Metabolomic Insights into Growth Performance of a Novel Allotriploid Fish Derived from Carassius cuvieri, Carassius auratus red var., and Cyprinus carpio.

Triploid fish have attracted considerable attention in aquaculture because of their sterility and rapid growth. In this study, a novel allotriploid fish (WA, 3n = 150) was obtained through distant hybridization of a female diploid hybrid fish (WR-II, 2n = 100) with a male allotetraploid fish (4nAT, 4n = 200). The measurable traits of WA exhibit significant differences from WR-II and its original parents (white crucian carp (WCC) and red crucian carp (RCC)). WA muscles exhibited higher protein, fat, and essential amino acid levels but lower moisture. Furthermore, WA enhanced growth performance and muscle hypertrophy compared to WCC and RCC. The transcriptomes and metabolomics of the muscle tissues of WA, WCC, and RCC were analyzed. In total, 3889 and 1863 differential expressed genes (DEGs) were identified in WA vs. WCC and WA vs. RCC, respectively. These DEGs were mainly enriched in pathways related to amino acid biosynthesis and oxidative phosphorylation. In total, 421 and 304 differential metabolites (DMs) were identified in WA vs. WCC and WA vs. RCC, respectively. These DMs were mainly enriched in the pathways related to glycerophospholipid and fatty acid metabolism. Integrated transcriptomic and metabolomic analyses revealed that the expression patterns of acta1, myh, myog, and aldoa were associated with changes in the abundance of oleoyl ethanolamide, betaine, inosine, docosahexaenoic acid (DHA), and PC (38:6), suggesting their potential involvement in the enhanced growth performance of WA. This study provides a potential genetic resource for aquaculture and identifies molecular features associated with enhanced growth performance in this allotriploid fish.