The origin of the Thai-Chitralada strain of Oreochromis. The origin of the Thai-Chitralada strain of Oreochromis

The Thai-Chitralada Oreochromis strain evolved from 50 fish that have been introduced to the Royal Chitralada Palace in Thailand. These fish were bred in Japan from a broodstock that had been imported from Egypt. In Thailand, the commercial Thai-Chitralada, integrates desirable traits for aquaculture, including high growth rate, reasonable fecundity and excellent performance in Asian countries. In 2010, few dozens of Thai-Chitralada fish were introduced to Israel from Thailand and a study to induce effective all-male farming has been initiated. Knowledge of hybridization history of this strain is crucial for controlling sex and thus, the objective of this study was to trace the origin of Thai-Chitralada using DNA barcoding and microsatellite genetic markers.COX1 and mitochondrial D-loop sequences of 19 Thai-Chitralada fish clustered into three groups comprising 6, 7 and 6 individuals that were homologous to the consensus sequences of O. aureus, O. niloticus and O. mossambicus, respectively. The allele ranges for microsatellites UNH168 and G7A exclude O. niloticus (Ghana) as potential contributor to the Thai-Chitralada strain. Genotyping for three microsatellites indicate overlap of alleles between Thai-Chitralada and O. niloticus (Egypt) and O. aureus, while O. mossambicus was not tested. Thus, our data based on mitochondrial and genomic analyses demonstrate that O. aureus, O. niloticus (Egypt) and O. mossambicus contributed to the formation of Thai-Chitralada and mono-sex culturing of Thai-Chitralada would thus require understanding the interactions between the different sex determination genes that are active in these contributing species.