Harlequin Rasbora Care Guide
The Harlequin Rasbora (Trigonostigma heteromorpha) is one of the most popular tropical freshwater fish in the UK. Known for its shimmering copper body and distinctive black triangular marking, it's a peaceful schooling fish ideal for planted and community aquariums.
In this guide, you'll learn everything you need to know about Harlequin Rasbora care, including tank size, water conditions, compatibility, feeding, and typical UK prices - plus how to buy or sell them locally.
Quick facts about Harlequin Rasboras
Harlequin rasboras are small shoaling fish native to Southeast Asia. They are hardy, peaceful, and highly adaptable, making them excellent fish for beginners and experienced aquarists alike.
They display their best colours in planted aquariums with subdued lighting.
Trigonostigma heteromorpha
4-5 cm
Southeast Asia (Thailand, Malaysia, Singapore)
60L (15gal)
5-8 years
Peaceful, shoaling
23-28°C
Omnivore (flakes, pellets, frozen, live foods)
6.0-7.5
£2-£5 per fish
How Many Harlequin Rasboras Should You Keep?
Harlequin rasboras are shoaling fish and should always be kept in groups.
- A minimum group of 6-8 is recommended
- Larger groups of 10+ help create more natural behaviour
- Larger shoals also improve confidence and colouration
Keeping too few can lead to:
- Stress and nervous behaviour
- Faded colours
- Reduced schooling behaviour
They are most impressive in large, active groups.
Ideal Tank Conditions for Harlequin Rasboras
Providing the right environment helps harlequin rasboras thrive and display natural behaviour.
- Tank Setup: Peaceful planted aquarium with open swimming areas
- Substrate: Dark substrate enhances colouration
- Plants & Decor: Dense planting, driftwood, and floating plants
- Water Conditions: Soft to moderately hard water with stable parameters
- Filtration & Flow: Gentle to moderate filtration
- Lighting: Moderate to subdued lighting preferred
They appreciate calm, well-established aquariums.
Compatibility with Other Fish
Harlequin rasboras are peaceful and ideal for community aquariums.
- Good Tankmates: tetras, corydoras catfish, honey gouramis, kuhli loaches, and small rainbowfish
- Avoid: aggressive fish and large predatory species
They mix well with most peaceful tropical fish.
Are Harlequin Rasboras Easy to Care For?
Harlequin rasboras are easy to care for and excellent for beginners.
They require:
- Stable water quality
- Proper shoal size
- A varied diet
- Peaceful tankmates
They are hardy and adaptable once established.
Harlequin Rasbora Price in the UK
In the UK, harlequin rasboras typically cost between £2-£5 per fish.
Prices vary depending on:
- Size and colour quality
- Availability
- Shop vs hobbyist sellers
They are affordable and widely available.
Where to Buy Harlequin Rasboras in the UK
Harlequin rasboras are widely available in UK aquarium shops and from hobbyist breeders.
Sourcing fish locally can:
- Reduce transport stress
- Improve survival rates
- Offer better value
TankMate UK helps connect fishkeepers who want to buy, sell, or rehome fish safely - without shipping.
Can You Sell Harlequin Rasboras?
Yes - harlequin rasboras are commonly bred and sold by hobbyists.
Selling locally is often the best option, as it:
- Minimises stress for the fish
- Avoids the risks of shipping
- Connects you with responsible aquarists
TankMate UK allows you to list fish quickly and find local buyers.
Feeding Harlequin Rasboras
Harlequin rasboras are omnivorous and easy to feed.
Key Tips:
- Feed high-quality flakes or micro pellets
- Supplement with frozen or live foods such as daphnia and brine shrimp
- Feed small portions 1-2 times daily
- Provide a varied diet for best colouration
They are enthusiastic but peaceful feeders.
Common Problems with Harlequin Rasboras
Faded colours, often caused by:
- Stress
- Poor water quality
- Insufficient group size
Nervous behaviour, linked to:
- Small shoals
- Aggressive tankmates
Disease outbreaks, caused by:
- Poor maintenance
- Sudden parameter changes
Why Harlequin Rasboras Are So Popular
- Peaceful and beginner-friendly
- Elegant copper and black coloration
- Ideal for planted aquariums
- Excellent schooling behaviour
- Hardy and adaptable
When kept correctly, harlequin rasboras create a calm and elegant display in community aquariums.
Frequently Asked Questions
Yes, they are hardy and easy to care for.
At least 6-8, though larger groups are recommended.
Yes, they make excellent community tankmates.
At least 60 litres, with planted areas and open swimming space.
Looking to Buy or Sell Harlequin Rasboras Locally?
TankMate UK connects fishkeepers who want to buy, sell, or rehome fish safely within their local area.
Whether you're adding peaceful schooling fish to your aquarium or passing fish on to a new home, you can:
- Browse fish available near you
- List your own fish in minutes
- Avoid the risks of shipping
Explore local listings with TankMate UK and find the right fish for your aquarium.