TankStockingHarlequin Rasbora Tank Mates
Harlequin rasboras are peaceful, hardy mid-water schoolers — a near-perfect beginner community fish.
Undemanding and non-aggressive, they mix with virtually every calm community species. Their copper-and-black colouring pops in a planted tank, and a tight school of eight or more behaves beautifully. The engine clears the usual peaceful crowd with few cautions.
Harlequin Rasbora key facts
The sourced figures the engine uses to judge Harlequin Rasbora pairings.
| Adult size | 4.5 cm |
|---|---|
| Minimum tank | 15 US gal |
| Minimum group | 8+ (shoal) |
| Temperament | Peaceful |
| Temperature range | 21–28°C |
| pH range | 5–7.5 |
| Bioload | Low |
| Swim level | Midwater |
| Beginner-friendly | Yes |
Sources & confidence (11 species)
These back the Harlequin Rasbora figures and the recommended tank mates above. Each figure is read from the TankStocking species database (v2026.06); below is the care reference behind it and how confident we are in that data. Confidence reflects the source quality, not whether any pairing is safe. Full source list and the welfare model are on the methodology page.
- Harlequin Rasbora Trigonostigma heteromorpha — Seriously Fish (seriouslyfish.com/species/trigonostigma-heteromorpha) high confidence
- Amano Shrimp Caridina multidentata — Aquarium Co-Op amano shrimp care; Aquadiction high confidence
- Black Neon Tetra Hyphessobrycon herbertaxelrodi — Seriously Fish / Aqua-Fish (Hyphessobrycon herbertaxelrodi) high confidence
- Black Phantom Tetra Hyphessobrycon megalopterus — Seriously Fish (Hyphessobrycon megalopterus) high confidence
- Bleeding Heart Tetra Hyphessobrycon erythrostigma — Seriously Fish (Hyphessobrycon erythrostigma) high confidence
- Bolivian Ram Mikrogeophagus altispinosus — Seriously Fish (seriouslyfish.com/species/mikrogeophagus-altispinosus) high confidence
- Brilliant Rasbora Rasbora einthovenii — Seriously Fish (seriouslyfish.com/species/rasbora-einthovenii) high confidence
- Bronze Corydoras Corydoras aeneus — Seriously Fish (seriouslyfish.com/species/corydoras-aeneus) high confidence
- Cardinal Tetra Paracheirodon axelrodi — Seriously Fish (seriouslyfish.com/species/paracheirodon-axelrodi) high confidence
- Celebes Rainbowfish Marosatherina ladigesi — Seriously Fish (seriouslyfish.com/species/marosatherina-ladigesi) high confidence
- Checker Barb Oliotius oligolepis — Seriously Fish — Oliotius oligolepis (https://www.seriouslyfish.com/species/oliotius-oligolepis/) high confidence
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Verdict
Top Harlequin Rasbora tank mates
A ranked shortlist: the species the engine clears with Harlequin Rasbora and that suit its size and temperament best — tap a name for its care guide, or use + Add to test the pairing in the planner.
| Species | Adult size | Temp range | Min group | Swim level | Why it works | Plan |
|---|---|---|---|---|---|---|
| Amano Shrimp | 5 cm | 18–27°C | 3+ (pair/group) | All levels | peacefulsize-safebeginner-friendlyPeaceful temperament, similar adult size | + Add |
| Black Neon Tetra | 3.5 cm | 23–27°C | 6+ (shoal) | Midwater | peacefulsize-safebeginner-friendlyPeaceful temperament, similar adult size | + Add |
| Black Phantom Tetra | 3.6 cm | 20–28°C | 6+ (shoal) | Midwater | peacefulsize-safebeginner-friendlyPeaceful temperament, similar adult size | + Add |
| Bleeding Heart Tetra | 6 cm | 21–28°C | 8+ (shoal) | Midwater | peacefulsize-safebeginner-friendlyPeaceful temperament, similar adult size | + Add |
| Bolivian Ram | 8 cm | 24–27°C | 2+ (pair/group) | Bottom | different swim levelpeacefulsize-safebeginner-friendlyUses the bottom zone, peaceful temperament, similar adult size | + Add |
| Brilliant Rasbora | 9 cm | 22–26°C | 6+ (shoal) | Midwater | peacefulsize-safebeginner-friendlyPeaceful temperament, similar adult size | + Add |
| Bronze Corydoras | 7 cm | 22–26°C | 6+ (shoal) | Bottom | different swim levelpeacefulsize-safebeginner-friendlyUses the bottom zone, peaceful temperament, similar adult size | + Add |
| Cardinal Tetra | 3 cm | 23–29°C | 6+ (shoal) | Midwater | peacefulsize-safebeginner-friendlyPeaceful temperament, similar adult size | + Add |
| Celebes Rainbowfish | 8 cm | 22–28°C | 6+ (shoal) | Midwater | peacefulsize-safebeginner-friendlyPeaceful temperament, similar adult size | + Add |
| Checker Barb | 5 cm | 20–25°C | 6+ (shoal) | Midwater | peacefulsize-safebeginner-friendlyPeaceful temperament, similar adult size | + Add |
No tank mates match these filters — try removing one.
Other engine-cleared options (not necessarily ideal)
These clear TankStocking's hard welfare checks with Harlequin Rasbora, but are larger, bolder, or otherwise less ideal than the shortlist above — read up before committing.
Anabantoids (Bettas/Gouramis)
Barbs
Corydoras
Invertebrates
Livebearers
Loaches
Oddball
Plecos & Catfish
Possible with care
These can work, but the engine flags something to watch — read the reason before you commit.
- Betta (Siamese Fighting Fish) — Territorial
- Paradise Fish — Aggression
- Cockatoo Dwarf Cichlid (Apisto Cacatuoides) — Territorial
- Convict Cichlid — Aggression
- Jewel Cichlid — Aggression
- Kribensis (Rainbow Krib) — Territorial
- Rainbow Shark — Aggression
- Redtail Black Shark — Aggression
Best avoided
A hard welfare check fires for each of these — don't mix them with Harlequin Rasbora.
- Chocolate Gourami — Species-only fish
- Kissing Gourami — Predation risk
- Licorice Gourami — Species-only fish
- Snakeskin Gourami — Predation risk
- Bala Shark — Predation risk
- Tinfoil Barb — Predation risk
- Discus — Temperature clash
- Electric Blue Acara — Predation risk
- Firemouth Cichlid — Predation risk, Territorial
- Green Severum — Predation risk
- Multifasciatus Shell-Dweller — Territorial, Species-only fish
- Oscar — Predation risk, Aggression
- Common Goldfish — Coldwater + tropical
- Fancy Goldfish — Coldwater + tropical
Keeping Harlequin Rasbora well: the detail
Beyond the table — the behaviour, the parameters that actually move the needle, and the mistakes that cost fish. Hobbyist context, not a verdict; the planner above is what judges your plan.
Water parameters in practice
Harlequins prefer soft, slightly acidic water (pH 6–7) but tolerate a fair range, which is why they are such a reliable beginner schooler. Keep them at 22–27 °C in a planted tank with some open swimming space. Stable water beats perfect water; they are not a demanding fish.
Why Harlequin Rasbora behaves the way it does
Harlequin rasboras come from the soft, acidic, tannin-stained blackwaters and peat swamps of South-East Asia, shoaling in the open water among submerged plants. The tight mid-water schooling is their natural anti-predator habit, and the copper-and-black wedge shows best against green planting. They are gentle, undemanding, and genuinely social.
Common Harlequin Rasbora stocking mistakes
The main mistake is keeping too few — a small group is shy and washed-out, so eight or more is the real minimum. The second is a stark, unplanted tank, which leaves an open-water shoaler exposed and nervous. There is little else to get wrong; this is a forgiving fish.
Early signs something is wrong
Loss of the deep copper colour, a fish hanging at the surface or apart from the group, and clamped fins are the usual early signals, generally water quality. They are hardy, so visible illness means a basic parameter has slipped. A good harlequin school is tight, bold, and richly coloured.
How tank size changes the answer
Eight in a 15-gallon is the sensible starting point. A 20-gallon-plus lets you run a dozen or more, where the schooling really shows, alongside a bottom group like cories. Give them open mid-water to shoal in and they fill the tank with movement.
Harlequin Rasbora community ideas
Each build is scored by the same engine as the planner — tap one to load it.
Harlequin + cory
✓ Good starter plan8× Harlequin Rasbora, 6× Bronze Corydoras
The textbook beginner community: a mid-water school over a bottom shoal.
Load this build in the planner ↑Harlequin + honey gourami
✓ Good starter plan8× Harlequin Rasbora, 1× Honey Gourami
A calm centrepiece above a rasbora school for a planted 15-gallon.
Load this build in the planner ↑Common questions
What fish can live with harlequin rasboras?
Almost any peaceful community fish: corydoras, neon and ember tetras, honey gouramis, dwarf cichlids and shrimp. Harlequins are gentle mid-water shoalers that rarely cause trouble.
How many harlequin rasboras should I keep?
At least eight. They are shoaling fish that feel secure and colour up best in a decent-sized group.
Are harlequin rasboras good for beginners?
Yes — they are hardy, peaceful, and tolerant of a range of conditions, making them one of the best first schooling fish.
More on Harlequin Rasbora
Related guides on TankStocking — each scored by the same welfare engine as the planner.
Care guides
Compatibility checks
Browse all fish
Compatibility is a planning estimate: individual temperament, tank layout, and group sizes all matter. Cycle the tank, add fish gradually, and watch how they behave. See the methodology or browse the full freshwater fish list.