Harlequin Rasbora

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Species group:

Other common names: Harlequin Fish, T-Bone

Scientific name: Trigonostigma heteromorpha

The basics:
The Harlequin Rasbora is a member of the Cyprinidae family of freshwater fish, a family which includes carp, minnows and barb. It is native to streams in peaty swamp forests of Malaysia and other Southeast Asian countries. Harlequin Rasbora are popular and colorful community tank fish, and do best in groups of six of more. They soon become distinguished additions to community tanks.

The black triangular patch on the Harlequin Rasbora’s body is what compares it to the colors of a harlequin, hence the name. The Rasbora has a lozenge-shaped body; an orange pink basal coloration (‘metallic red’ for some) spreads from the head to the fish’s caudal penuncle. The precise hue is dependent on water conditions in which the fish is bred. The triangular black marking occurs in the posterior half of the fish’s body, starting from the dorsal fin and tapering towards the caudal penuncle. Pectoral fins are above the gill cover; whole pelvic fins appear along the ventral side of the Rasbora’s body. The fins have a reddish tint.

0-2 inches

Harlequin Rasbora are peaceful and adaptable to a variety of water conditions and tankmates.
The Harlequin Rasbora has an active but non-aggressive disposition towards other species. They have a natural disposition towards schooling in groups of ten.

A 10 to 15 gallon tank is sufficient for housing a small group (8-10) of Harlequin rasboras. Aquariums with good filtration conditions deliver the best results. A densely planted environment with dark soil substrates suits Rasboras well. Pieces of driftwood can also be added to the tank. Peat filtration is also provided in some cases.

72.00-78.00 °F


100.000-0.000 mg/L


larger shoals, peaceful community fish, peaceful fish, dark purpleblue colour, metallic copper color


larger predators, soft enough water, frequent water changes


aquarium vegetation, triangular black patch, open swimming space, midwater section

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