Interspecific Mating Behavior Between Introduced Zacco platypus and Native Opsariichthys evolans in Taiwan

Introduced freshwater fishes considerably influence the ecology and populations of native species. Previous research has revealed that introduced Zacco platypus may hybridize with chubs that are sister but distinct genera. However, we have little knowledge of Z. platypus' mate choice or its impact on Taiwanese chubs. Therefore, this study identified the interspecific mating behavior between introduced Z. platypus and native Opsariichthys evolans and evaluated the former's invasive impact on cohabitants. Our observations showed that interspecific mating pairs do occur between Z. platypus male(s) and O. evolans female(s). Fifty-three percent of spawning events were interspecific mating and only 43% were between native O. evolans mating pairs. This study showed that Z. platypus male satellites might prefer to engage with Z. platypus, while O. evolans might engage by chance. However, introduced males of Z. platypus may be unable to recognize conspecific females. Meanwhile, introduced females of Z. platypus also have a mate choice preference for males of Z. platypus. Therefore, Z. platypus male hybridization might significantly reduce the successful mating ratio of O. evolans, leading to a dramatic reduction in native O. evolans offspring in the future.