The introduction of non-native species through the aquarium trade poses a significant threat to ecosystems, communities, and native populations. The globally popular ornamental bee shrimp Caridina logemanni Klotz and von Rintelen (2014) established an alien population in the headwaters of a spring-fed stream in Tokyo, Japan, in 2018, a site previously reported as the first known location worldwide where the species successfully established in the wild. This study reports that the species has continued to inhabit the area stably for six years since its establishment. Additionally, to accumulate the information necessary to prevent further invasions and expansions of this species, we estimated the phylogenetic position of the introduced population based on mitochondrial DNA and compared environmental conditions between its native and introduced habitats. A haplotype detected in the alien population of bee shrimp was identical to that of the aquarium lineage, supporting that this population originated from the aquarium trade. Although the climate of Tokyo differs significantly from that of the native habitat of this species in Hong Kong, our results suggest that the bee shrimp can become established in an environment where the water temperature is stable throughout the year. To prevent the escape of ornamental species into the wild and ensure the sustainable management of ornamental shrimp culture, it is crucial to raise awareness of the risks associated with non-native species in the aquarium trade and implement legal restrictions to mitigate the spread of ornamental species.
