Harlequin Rasbora - Trigonostigma heteromorpha : Complete Fish Profile & Care Guide
Table of contents
Introduction
Harlequin Rasboras (Trigonostigma heteromorpha) are a wonderful addition to any aquarist's collection, with their striking appearance and lively behaviour. 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 behaviour.
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 Photos
Sexual Dimorphism
The process of identifying the gender of Harlequin Rasboras 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.
Quick Facts
| Scientific Name | Trigonostigma heteromorpha |
|---|---|
| Year Described | 1904 |
| Other Names | Red Rasbora, Harlequin Fish, Red Razor |
| Classification | Actinopterygii |
| Order | Cypriniformes |
| Family | Cyprinidae |
| Genus | Trigonostigma |
| Origins | Thailand , Malaysia , Singapore , Indonesia |
| Max Size | 5 cm |
| Temperament | Peaceful |
| Aquarium Level | Middle - Top |
| Difficulty | Beginner - Intermediate |
| Shoaling | Yes |
| Best kept as | Groups 6+ |
| Diet & Feeding | Omnivore |
| Reproduction | Egg Depositor |
| Lifespan | Up to 8 Years |
Water Parameters
| Water Type | Freshwater |
|---|---|
| pH | 6 - 7 |
| GH | 2 - 15 |
| TDS | 18 - 215 |
| ℉ | 72 - 82 |
|---|---|
| ℃ | 22 - 28 |
The Harlequin Rasbora has been featured on the following stamps.
Featured Species
Natural Habitat
Harlequin Rasboras are native to Malaysia, Sumatra, and southern Thailand, located in Southeast Asia. In addition to these areas, you can also find Harlequin Rasboras in the Nee Soon Swamp in Singapore, where they inhabit slow-moving blackwaters in streams, rivers, and swamp forests. Harlequin Rasboras typically occupy habitats with water that is slightly acidic, neutral, and soft.
These environments are usually shaded, owing to the forest canopy above and the dense vegetation surrounding them. Fallen leaves, twigs, and branches often cover the substrates, creating a perfect environment for the fish to feed, shelter, rest, and hide. Adding Harlequin Rasboras to your aquarium is an excellent way to showcase their unique beauty and contribute to their conservation efforts.
Breeding
Breeding Harlequin Rasboras can be a challenging yet rewarding experience for aquarists. To successfully breed these fish, it is recommended to set up a separate breeding tank with soft, shallow water and peat filtration. Broad-leaved plants should also be added to provide a suitable spawning site. Spawning usually occurs in the morning, triggered by the first rays of sunlight. Females can lay up to 250 eggs on the underside of leaves, with males fertilizing them using a shaking motion.
The process may last up to two hours, with the female laying six to twelve eggs at a time. After the eggs are laid, it is crucial to remove the parents from the breeding tank to prevent them from eating the eggs. The tank should be covered to prevent light exposure and fungus growth. Hatching occurs around 24 hours after laying, and the fry will become free-swimming 72 hours later.
These tiny fry require small-grade foods, starting with infusoria and gradually moving on to more significant foods as they grow. Frequent partial water changes are necessary as the fry is highly sensitive to changes. Overall, breeding Harlequin Rasboras requires careful attention to water quality and the right environment for the fish to spawn.
Diet & feeding
Harlequin Rasboras have an omnivorous diet and will accept a variety of food sources; however, their small mouths require relatively small-sized foods. During feeding time, Harlequin Rasboras become very active and will eagerly consume high-quality dried foods like flakes or pellets. To ensure a balanced diet, it is recommended to supplement their diet with small live and frozen foods such as daphnia, brine shrimp, and bloodworms.
