A small, peaceful, and highly active schooling fish known for the striking glowing orange or copper stroke above its thin black 'pork-chop' marking. Smaller and much more slender than the standard Harlequin Rasbora, they are perfect for planted nano aquariums. They must be kept in schools of at least 6 to feel secure and display their best colors.
Copper Harlequin Rasbora At a Glance
Copper Harlequin Rasbora Tank Requirements
Will Copper Harlequin Rasbora fit in your tank?
Care guides tell you what Copper Harlequin Rasbora needs, the next question is whether your tank can safely provide it. Test Copper Harlequin Rasbora against your tank size, maintenance needs, and the fish you already keep before you buy.
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Copper Harlequin Rasbora Water Parameters
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Copper Harlequin Rasbora Temperament & Compatibility
Copper Harlequin Rasbora Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Standard
The standard wild-type Trigonostigma hengeli. Males are slightly more brightly colored and slimmer than females, but they are sold and kept mixed in shoals.
Same care requirements as the base species
Also known as: Wild Type
Copper Harlequin Rasbora Care Guide Summary
The Copper Harlequin Rasbora, scientifically known as Trigonostigma hengeli, belongs to the Cyprinids family group. Adults reach a maximum size of approximately 3 cm and have a fusiform body shape with a moderate growth rate. Classified as peaceful, this species primarily occupies the surface and mid-level zones of the aquarium and produces a low level of biological waste.
To thrive, the Copper Harlequin Rasbora requires a freshwater only aquarium with a minimum volume of 38 litres and a tank length of at least 45 cm. Water temperature should be maintained between 23°C and 28°C, with a pH range of 5–7.5 and a general hardness of 1–10 dGH. A moderate water flow is preferred.
Due to its specialist needs, the Copper Harlequin Rasbora is best suited for fishkeepers who can provide a carefully planned setup. The Copper Harlequin Rasbora is typically available in one standard form.
Copper Harlequin Rasbora Habitat Setup
When setting up an aquarium for the Copper Harlequin Rasbora, a moderate water flow best suits their natural preferences. Because this species occupies the surface and mid-level zones, the aquarium layout should prioritise adequate surface area with floating cover to make them feel secure near the waterline and open swimming space in the centre of the tank for free movement. Useful additions include leaf litter or blackwater tannins to replicate their natural soft-water habitat, dense planting to provide cover, break sightlines, and reduce stress, and floating plants to diffuse overhead light and create shaded areas. Keepers should note that a tight-fitting lid is essential, as this species is a known jumper.
Copper Harlequin Rasbora Compatibility Notes
Classified as peaceful, the Copper Harlequin Rasbora is a schooling species that feels most secure in a sizeable group, where natural shoaling behaviour reduces stress and brings out their best colours. Selecting tankmates that favour different water layers from the surface and mid-level zones can help reduce competition and territorial overlap.
Copper Harlequin Rasbora Recommended Tank Sizes
Standard aquarium sizes that meet the minimum volume and length requirements for Copper Harlequin Rasbora.
10 Gallon Standard
15 Gallon Standard
20 Gallon High
20 Gallon Long
29 Gallon Standard
30 Gallon Breeder
Show 22 more tank sizes
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Frequently Asked Questions About Copper Harlequin Rasbora
How big does Copper Harlequin Rasbora get?
Copper Harlequin Rasbora (Trigonostigma hengeli) typically reaches a maximum adult size of approximately 3 cm. They have a fusiform body shape and a moderate growth rate.
What tank size does Copper Harlequin Rasbora need?
A minimum aquarium volume of 38 litres and a tank length of at least 45 cm are recommended for Copper Harlequin Rasbora. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Copper Harlequin Rasbora need?
Copper Harlequin Rasbora thrives in freshwater only conditions with a temperature range of 23–28°C, a pH between 5 and 7.5, and a general hardness of 1–10 dGH. A moderate water flow is preferred.
Is Copper Harlequin Rasbora peaceful or aggressive?
Copper Harlequin Rasbora is classified as peaceful with an aggression score of 1 out of 10. They are generally well-suited to peaceful community tanks.
How many Copper Harlequin Rasbora should be kept together?
Copper Harlequin Rasbora is a schooling species and should be kept in groups of at least 6. Larger groups help distribute aggression and encourage natural schooling behaviour.
Does Copper Harlequin Rasbora have any special tank requirements?
Yes. Copper Harlequin Rasbora benefits from plants - densely covered, plants - floating, and leaf litter/blackwater in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.
Does Copper Harlequin Rasbora need a lid on the tank?
Yes. Copper Harlequin Rasbora is a known jumper, and a tight-fitting lid or cover is essential to prevent escape. Even a small gap can be enough for a determined fish to leap out.
Top Tank Mates for Copper Harlequin Rasbora
These fish are strong compatibility matches for Copper Harlequin Rasbora based on water preferences, temperament, adult size, and tank behavior.
Golden Bristlenose Pleco
Ancistrus sp. L144
Ideal Tank MatesMalaysian Trumpet Snail (MTS)
Melanoides tuberculata
Ideal Tank MatesAssassin Snail
Anentome helena
Ideal Tank MatesBristlenose Pleco
Ancistrus cf. cirrhosus
Ideal Tank MatesRamshorn Snail
Planorbidae fam.
Ideal Tank MatesPlants That Suit Copper Harlequin Rasbora
These plants pair well with Copper Harlequin Rasbora based on shared water preferences, layout fit, and how likely they are to hold up in the same aquarium.
Afzel's Anubias
Anubias afzelii
Amazon Sword
Echinodorus amazonicus
Anacharis
Egeria densa
Anubias Barteri
Anubias barteri
Baby Tears
Lindernia rotundifolia
Balansae
Cryptocoryne crispatula
Fish Similar to Copper Harlequin Rasbora
Harlequin Rasbora
Trigonostigma heteromorpha
A highly popular, peaceful schooling fish recognizable by its metallic copper/orange body and the distinct black triangular 'porkchop' patch on its hindquarters. Originating from peat swamps and blackwater streams in Southeast Asia, they are active swimmers that thrive in heavily planted aquariums with gentle to moderate water flow.
Espei Rasbora (Lambchop Rasbora)
Trigonostigma espei
A small, peaceful schooling fish native to Southeast Asia. Closely related to the Harlequin Rasbora but distinguished by a more copper-orange coloration and a thinner, 'lambchop' shaped black marking on its flank. They thrive in heavily planted, mature aquariums with gentle water flow and slightly acidic water.
Emerald Eye Rasbora
Brevibora dorsiocellata
A small, active schooling fish native to Southeast Asia, famous for the striking black-and-white spot on its dorsal fin and its reflective 'emerald' eyes. They are highly peaceful and thrive in heavily planted or blackwater aquariums. As a strict schooling species, they must be kept in groups to feel secure, establish a natural hierarchy, and display their best colors.
Blackline Rasbora
Rasbora borapetensis
The Blackline Rasbora, often sold as the Red-tailed Rasbora, is a hardy and highly active schooling fish native to Southeast Asia. Recognizable by a bold black lateral line topped with gold and a bright red caudal fin, they are peaceful but energetic. They require plenty of horizontal swimming space in the middle to upper levels of the aquarium and must be kept in schools to feel secure.
Brilliant Rasbora
Rasbora einthovenii
The Brilliant Rasbora is a peaceful, highly active schooling fish native to the forest streams and peat swamps of Southeast Asia. Known for its shimmering silver body and distinct dark lateral stripe, they thrive in gently flowing, heavily planted blackwater setups with subdued lighting. They are known jumpers, requiring a tight-fitting lid.
Dwarf Rasbora
Boraras maculatus
A tiny, peaceful shoaling fish native to the blackwater streams and peat swamps of Southeast Asia. Known for their striking red/orange coloration and distinct dark body spots. They are an excellent choice for heavily planted nano tanks and peaceful dwarf shrimp setups. Because of their minute size, they are easily outcompeted for food and predated upon by larger fish.