剑尾鱼 jiàn wěi yú Xiphophorus，Swordtail

剑尾鱼【Xiphophorus，Swordtail】属花鳉科剑尾鱼属的一种热带鱼。产于墨西哥、危地马拉等地的江河流域。性情温和，很活泼，可与小型鱼混养。雄鱼尾鳍下叶有一呈长剑状的延伸突。与新月鱼（Platy）近缘，广泛用于遗传及医学研究。剑尾鱼原为绿色，体侧各具一红色条纹，但已培育出许多花色品种。

百度翻译提供：

Xiphophorus (swordtail) is a tropical fish belonging to the genus Xiphophorus in the medaka family. It is produced in the river basins of Mexico, Guatemala and other places. Mild temperament, very lively, can be mixed with small fish. The lower leaf of male tail fin has a long sword like extension. It is closely related to platy and widely used in genetic and medical research. Swordfish was originally green with red stripes on both sides, but many varieties of colors have been developed.