The Harlequin Tetra, also known as the Rasbora Heteromorpha, is a small freshwater fish species that is native to Southeast Asia. It is a popular choice for aquarium enthusiasts due to its attractive appearance, hardiness, and peaceful nature.

The Harlequin Tetra has a slender, elongated body that can grow up to 2 inches in length. It has a silver body with a distinctive black and orange triangular patch on the upper half of its body, which gives it its harlequin-like appearance. The fins are typically transparent, with a reddish tint. They are active swimmers and prefer to be kept in groups of 6 or more in a well-planted aquarium with plenty of hiding places. They are omnivorous and will eat a variety of foods, including flakes, pellets, and live or frozen foods.