Learn Harlequin Rasboras care with expert tips on tank setup, diet, tank mates, lifespan, and more—perfect for beginners and seasoned aquarists alike.
Introduction 🌿
If you’re looking to bring a burst of color and energy into your home aquarium, the Harlequin Rasbora is one of the most rewarding fish to keep. I’ve cared for them for years, and this guide will walk you through everything—from creating the perfect tank setup to feeding, lifespan, and choosing tank mates.
Short answer: Harlequin Rasbora care is simple, but true success comes from perfecting water conditions, tank setup, and diet.
What is the Harlequin Rasbora? 🧡
The Harlequin Rasbora (Trigonostigma heteromorpha) is a small, peaceful freshwater fish native to Southeast Asia. Their shimmering copper-pink bodies and distinct black wedge marking near the tail make them one of the most beautiful schooling fish for any freshwater tank.
In my tanks, their color truly pops against a dark substrate and lush green plants. When the morning light hits, it’s like watching tiny orange lanterns drift through water.
Short answer: The Harlequin Rasbora is a vibrant, social schooling fish perfect for community tanks.
Size, Life Span & Growth 🧬
Size: Most Harlequin Rasboras grow to about 1.5–2 inches long. They’re petite, but their personality and color more than make up for it.
Life Span: With proper care, they live 4–6 years on average and can reach 7+ years in excellent conditions. In my tank, the oldest one lived to almost eight years—proving how far good care goes.
Short answer: They stay small and live up to six years or more in stable, clean environments.
Harlequin Rasbora Tank Setup 🪴
Creating the right environment is key to keeping your Rasboras healthy and happy.
Tank Size & Layout
A 10-gallon tank can work for a small group, but I highly recommend 20–30 gallons or larger if you want a lively school. They love horizontal swimming space, so go for a tank that’s longer rather than tall.
Short answer: Bigger tanks with plenty of open space make your Rasboras confident and vibrant.
Water Parameters
To mimic their natural tropical habitat, aim for:
- Temperature: 72–80°F (22–27°C)
- pH: 6.0–7.5
- Hardness: 2–15 dGH
- Flow: Gentle
- Lighting: Soft and subdued
I like to use an adjustable filter so the current stays gentle. Once, I had the filter flow too strong, and they hid most of the day. When I reduced it, they immediately began schooling again.
Short answer: Soft, warm water and gentle flow are the sweet spot for Harlequin Rasboras.
Decor & Plants 🌱
Use a dark substrate like black sand or fine gravel—it deepens their colors beautifully. Fill the tank with dense vegetation like Java Fern, Anubias, or Cryptocoryne, and leave open space in the center for free swimming.
I also love adding a few Indian almond leaves or a piece of driftwood. These release natural tannins, creating a cozy, tea-colored “blackwater” look Rasboras adore.
Short answer: Combine dark substrate, soft light, and leafy plants to mimic their natural home.
Schooling & Social Behavior 👯
Harlequin Rasboras are true schooling fish. Always keep at least 8–10 together—more if possible. When kept in smaller numbers, they can appear shy or stressed.
When I expanded my group from 6 to 12, their transformation was instant—they schooled tightly and explored fearlessly.
Short answer: Keep them in groups of 8+ for confidence, color, and natural schooling behavior.
Harlequin Rasbora Diet 🍽️
Feeding these little jewels is straightforward but variety is key.
What They Eat
In the wild, they feed on insects, larvae, and zooplankton. In your tank, provide:
- High-quality tropical flakes (like TetraMin Tropical Flakes). To purchase a container of your own, click here.
- Small pellets suitable for community fish
- Frozen or live foods like brine shrimp, daphnia, and bloodworms
I rotate between flakes during the week and frozen Hikari Brine Shrimp every weekend. The difference in color and energy after a live feeding day is amazing.
Short answer: Give them a balanced mix of flakes, pellets, and frozen/live foods for optimal color and health.
Feeding Schedule
Feed small portions once or twice daily, only as much as they’ll eat in two minutes. Overfeeding can foul water quickly in smaller tanks.
I also use a feeding ring to keep food from drifting, which helps ensure all fish get their share.
Short answer: Feed lightly and consistently—variety and moderation keep them healthy.
Harlequin Rasbora Tank Mates 🐟
These fish are peaceful and social, making them perfect for community setups.
Best Tank Mates
Ideal companions include:
- Small tetras (like neon or ember tetras)
- Corydoras catfish
- Dwarf gouramis
- Snails and peaceful shrimp
In my community tank, they share space with neon tetras and panda corys—it’s like a coordinated underwater dance.
Short answer: Choose peaceful, similarly sized species—they thrive in calm company.
Tank Mates to Avoid 🚫
Avoid aggressive or fin-nipping species like larger barbs or cichlids. Even an overly curious betta can sometimes stress them.
If you want to try pairing with a betta, ensure a heavily planted tank and monitor behavior closely.
Short answer: Skip aggressive fish; peaceful companions make for stress-free harmony.
Types of Harlequin Rasbora 🌈
There are a few variations of this beautiful fish, each with its own unique flair:
- Classic Harlequin: Copper-pink body with a bold black wedge
- Golden Harlequin: Lighter, gold-toned variant
- Black Harlequin: Deeper contrast with an expanded wedge mark
- Blue/Steel variant: Subtle metallic blue tint
I once added a few golden Harlequins to my main group—the color mix created a gorgeous contrast under warm LED lighting.
Short answer: Multiple color varieties exist, but care is identical for all.
Harlequin Rasbora Life Span & Long-Term Care ⏳
With love and consistency, these fish can live typically 3 to 5 years, but they can live longer, with some reaching 5 to 8 years with proper care.
Keep water parameters stable—avoid sudden temperature or pH swings. Perform weekly water changes (20–30%) and monitor ammonia, nitrite, and nitrate levels.
Rasboras do best in mature tanks where plants, substrate, and filtration are well-established. I’ve seen them flourish when tanks have been running for several months before introduction.
Short answer: Stable conditions and regular maintenance are the secrets to long-lived Rasboras.
Health & Common Problems 💧
Harlequin Rasboras are hardy, but poor water quality or stress can lead to problems.
Common issues include:
- Ich (white spots) from temperature swings
- Fin rot caused by poor hygiene or aggressive tank mates
- Bacterial infections due to unclean substrate or uneaten food buildup
Watch for color fading, clamped fins, or sluggish swimming. If you notice these signs, check your water parameters immediately and do a partial water change.
Once, I saw one of mine isolating itself and losing color. After adjusting the filter flow and performing a small water change, it perked right up.
Short answer: Clean water and calm tank conditions prevent nearly every common issue.
Breeding Harlequin Rasboras 🐣
Breeding them is possible, though a bit challenging for beginners.
Use a separate breeding tank with soft, slightly acidic water (pH around 6.0) and a temperature near 78°F. Add broad-leaf plants like Cryptocoryne for the females to lay eggs on.
Feed the pair plenty of live foods like daphnia and brine shrimp to condition them. Once eggs are laid, remove the parents—otherwise, they’ll eat the eggs.
Short answer: Breeding is possible in soft, warm water with careful preparation and parental separation.
My Personal Tips & Lessons Learned 💡
Here are a few insights I’ve gathered over the years:
- Use a 20-gallon long tank with dark sand, live plants, and gentle lighting.
- Always keep them in groups of 8+ for natural schooling.
- Add Indian almond leaves or driftwood to darken the water and reduce stress.
- Avoid strong filter currents—they prefer calm flow.
- Rotate foods for color and health—flakes, pellets, and frozen foods each play a role.
- Most importantly: patience. Don’t rush tank cycling or parameter adjustments.
Short answer: A calm, planted, stable tank setup brings out the best colors and behavior in your Rasboras.
Summary / Quick Reference Card 📋
| Topic | Key Points |
|---|---|
| Tank Size | 10 gal minimum, 20+ gal ideal for schooling |
| Water Temp | 72–80 °F (22–27 °C) |
| pH & Hardness | 6.0–7.5 pH, 2–15 dGH |
| School Size | 8–10+ fish |
| Diet | Flakes, pellets, frozen/live food mix |
| Tank Mates | Peaceful fish like tetras, corys, gouramis |
| Lifespan | 4–6 years (up to 7+ with care) |
| Common Issues | Ich, fin rot, stress |
| Best Setup | Planted tank, dark substrate, soft light |
FAQs 🙋♀️
What’s the maximum size of a Harlequin Rasbora?
They usually reach 1.5–2 inches long—perfect for community tanks.
How long do Harlequin Rasboras live?
Typically 4–6 years, though some live beyond 7 with consistent care.
Can I keep Harlequin Rasboras with a Betta?
Yes, but only if the Betta is calm and the tank is heavily planted to provide hiding spaces.
What’s the best food for Harlequin Rasboras?
High-quality flakes or pellets daily, with frozen or live foods like brine shrimp a few times a week for color and health.
How many Harlequin Rasboras can live in a 20-gallon tank?
Around 10–12 Rasboras can comfortably thrive in a 20-gallon long tank.
Conclusion 🌊
Caring for Harlequin Rasboras is both simple and incredibly rewarding. They bring energy, color, and harmony to your aquarium—especially when kept in a calm, planted environment with stable water and a balanced diet.
From my experience, few fish are as graceful or peaceful. The moment you see them schooling together under soft light, you’ll understand why aquarists love them so much.
Short answer: With gentle care, balanced feeding, and a peaceful tank setup, Harlequin Rasboras will reward you with years of vivid color and lively personality.