Harlequin Rasbora — Fish Profile
Trigonostigma heteromorpha
Quick Specs
| Adult Size: | 2.0" |
| Temperament: | peaceful |
| Care Level: | beginner |
| Min Tank Size: | 10 gallons |
| Temperature: | 73-79°F |
| pH Range: | 5.5-7.0 |
| Diet: | omnivore |
| Origin: | Southeast Asia |
| Lifespan: | 5-8 years |
Overview
Harlequin rasboras are peaceful schooling fish with a distinctive black triangular patch. Perfect for planted community tanks.
Care Guide for Harlequin Rasbora
Tank Setup
Harlequin Rasbora requires a minimum tank size of 10 gallons. Maintain water temperature between 73°F and 79°F, with a pH range of 5.5 to 7.0. A properly sized tank with adequate filtration and regular water changes is essential for long-term health. When housing Harlequin Rasbora with other species, always choose a tank size that accommodates the most demanding fish in the community.
Feeding
Harlequin Rasbora is a omnivore feeder. Provide a varied diet appropriate for omnivore species to ensure optimal health and coloration. Feed small portions 2–3 times daily, and remove uneaten food after a few minutes to maintain water quality.
Temperament & Compatibility
This species is classified as peaceful. Harlequin Rasbora reaches an adult size of 2.0 inches and has a care level of beginner. Always research compatibility before adding new fish to an established aquarium. Individual temperament can vary, so monitor new introductions closely for the first 48 hours.
Origin & Lifespan
Harlequin Rasbora originates from Southeast Asia and has an expected lifespan of 5-8 years when kept in proper water conditions with appropriate tank mates and diet.
Compatible Tank Mates
🟢 Good Tank Mates
🟡 Caution Tank Mates
🔴 Risky Tank Mates
Compatibility Results for Harlequin Rasbora
All 69 compatibility checks involving Harlequin Rasbora:
Recommended for Harlequin Rasbora
Seachem Flourish Excel — $12.99Plant supplement for planted tanks
Expert Care Tips for Harlequin Rasbora
- Nano tank suitable: Harlequin Rasbora can thrive in smaller tanks (10+ gal), but skip the bowl — even small fish need filtration and a heater.
- Tropical range: Keep Harlequin Rasbora at 73–79°F. A 50W heater per 10 gallons is a safe rule of thumb for stable temperature.
- Adaptable pH range: Harlequin Rasbora accepts pH 5.5–7.0. Most tap water falls within this range, but always test and acclimate slowly.
- Peaceful community fish: Harlequin Rasbora works well in community tanks. Still, avoid housing with fish large enough to eat them — a 2.0" fish is vulnerable to anything with a mouth bigger than 2×.
- Acclimation: Always drip-acclimate Harlequin Rasbora over 30–45 minutes. Match temperature and pH gradually to prevent osmotic shock.