Max Size: 5cm

Harlequin Rasbora (Trigonostigma heteromorpha)

Harlequin Rasboras (Trigonostigma heteromorpha) are a wonderful addition to any aquarist's collection, with their striking appearance and lively behavior. These peaceful and hardy fish are perfect for a community aquarium or a nano aquascape.

Keeping Harlequin Rasboras in groups of eight or more will create a stunning display and allow you to observe their natural shoaling behavior. These fish are compatible with most small temperate fish, such as Tetras, Bettas, Dwarf Barbs, and Gouramis, but should not be housed with larger or more aggressive species.

For the ideal aquarium setup, mimic their natural environment with soft, acidic water, and plenty of plants, driftwood, and leaf litter. Providing dim lighting and floating plants will create a natural feel and add to their comfort.

Harlequin Rasboras have a copper-red metallic body with a signature black triangular wedge and red-lined fins. Captive-bred black and gold strains are also available, adding to the variety of this already captivating fish.

Feeding Harlequin Rasboras is relatively easy; they are omnivores and will readily accept dried foods like flakes and pellets, supplemented with small live and frozen foods such as daphnia, brine shrimp, and bloodworms.

Overall, Harlequin Rasboras are a beautiful, peaceful, and fascinating addition to any aquarium, providing a lively display and adding a touch of elegance to any aquascape.


Harlequin Rasbora
Harlequin Rasbora
Longfin Harlequin Rasbora
Harlequin Rasbora
Harlequin Rasboras
Blue Harlequin Rasbora
Harlequin Rasboras
Harlequin Rasboras
Harlequin Rasboras
Harlequin Rasbora
Harlequin Rasbora
Harlequin Rasbora
Harlequin Rasbora
Quick Facts
Scientific NameTrigonostigma heteromorpha
Year Described1904
Other NamesRed Rasbora, Harlequin Fish, Red Razor
OriginsIndonesia, Malaysia, Singapore, Thailand
Aquarium LevelMiddle - Top
DifficultyBeginner - Intermediate
Best kept asGroups 6+
Lifespan3 - 5 years
Water Parameters
Water TypeFreshwater
PH5.5 - 7.0
GH2 - 15
TDS18 - 215
72 - 80℉
22.2 - 26.7℃


In the home aquarium, the Harlequin Rasbora will readily accept most good quality dried foods such as granules, flakes and sinking pellets. These modern food products have been developed to provide all adequate nutrition to maintain your fish's health and dietary requirements.

Providing additional foodstuffs such as live, frozen, and freeze-dried meals such as bloodworm, daphnia, and tubifex once or twice a week will provide additional benefits to your fish's health and well-being but is not a must for this fish.

It should be noted that bloodworms should only be given as an occasional treat and should not be used as the staple diet as they are difficult for fish to digest and can potentially cause blockages.

This fish is an omnivore in the wild, meaning it will consume some vegetable matter. Although most modern fish foods take this into account and include them in their products, you can still supplement your fish's diet with blanched vegetables such as spinach, broccoli, and zucchini. Ensure you do not overfeed your fish and remove any leftovers the following day.

Sexual Dimorphism

The process of identifying the gender of Harlequin Rasbora is relatively straightforward. Males tend to have more striking colours and a slimmer physique than their female counterparts. In addition, the triangular patch on the male's body is typically rounder and more elongated than in females. On the other hand, females tend to have a plumper body shape and less distinct colouration compared to males.

The Harlequin Rasbora has been featured on the following stamps

Singapore - 1962