Identification of wild tilapia species in the main rivers of south China using mitochondrial control region sequence and morphology

Tilapias are now the most common alien fish in the rivers of South China and the dominant species in many sites. However, wild tilapia species have not been well-characterized or studied systematically. In this study, mitochondrial DNA control regions (mtDNA CR) and morphological characteristics were used to identify invasive tilapia species. Using mtDNA CR sequence, we identified Oreochromis niloticus, Tilapia zillii, Oreochromis aureus, Sarotherodon galilaeus, and hybrids of Oreochromis mossambicus and O. niloticus in the rivers of South China, and characterized their morphological features. Of the 5 species, O. niloticus and T. zillii were the most abundant in the rivers of South China. Furthermore, the distribution of O. niloticus may be related to their large numbers in the aquaculture industry, and the explosion of T. zillii invasion may be related to their strong capacity for environmental adaptation. These findings are beneficial for identifying wild tilapia populations and for the specific control of invasive tilapia species.