Hyriopsis

Hyriopsis is a genus of freshwater mussels in the family Hyriidae, order Unionoida. These aquatic bivalves are native to East Asia, with species occurring in rivers and lakes of China, Japan, and surrounding regions. The genus includes several species, among them Hyriopsis cumingii and Hyriopsis schlegelii, which have been the focus of commercial freshwater pearl culture.

Hyriopsis shells are elongated and commonly dark to greenish on the exterior, with a nacreous inner layer that produces lustrous pearls when cultured. Reproduction involves males and females; females release glochidia, which are microscopic larvae that must attach to a specific fish host to complete development into juvenile mussels. After a period parasitizing the fish, the glochidia metamorphose and settle as juvenile mussels on the river substrate.

Economically, Hyriopsis cumingii is a principal source of freshwater cultured pearls in China, while Hyriopsis schlegelii has been used in pearl production elsewhere in East Asia. The genus faces conservation concerns due to habitat loss, water pollution, and collection pressures; management and hatchery-based propagation programs aim to sustain populations and the pearl industry. Research on breeding and disease resistance continues to support sustainable aquaculture of Hyriopsis species.