Harlequin Rasbora Overview
The Harlequin Rasbora (Trigonostigma heteromorpha) is a freshwater fish from the family Cyprinidae. It thrives at temperatures of 22–27 °C with a pH of 6.0–7.8, requiring a minimum tank size of 60 litres. Classic community fish with a distinctive black triangular patch. Schools tightly near the surface; looks stunning in large groups of 10+.
Quick fact: Trigonostigma heteromorpha belongs to the family Cyprinidae. Care level: beginner.
Harlequin Rasbora Scientific Classification
| Rank | Classification |
|---|---|
| Family | Cyprinidae |
| Genus | Trigonostigma |
| Species | Trigonostigma heteromorpha |
| Water type | freshwater |
Harlequin Rasbora Natural Habitat
Harlequin Rasbora Appearance & Size
Harlequin Rasbora Behavior & Temperament
Schools tightly near the surface; looks stunning in large groups of 10+
| Trait | Value |
|---|---|
| Temperament | Classic community fish with a distinctive black triangular patch |
| Schooling | Yes |
| Activity level | active |
Harlequin Rasbora Water Requirements
| Parameter | Ideal Range | Notes |
|---|---|---|
| Temperature | 22–27°C (72–81°F) | Use a reliable adjustable heater |
| pH | 6–7.8 | Avoid sudden swings |
| Hardness (GH) | soft dGH | Soft to moderately hard |
| Ammonia | 0 ppm | Any detectable ammonia signals a problem |
| Nitrite | 0 ppm | Toxic even at low levels |
| Nitrate | <20 ppm | Manage through regular partial water changes |
| Min. tank | 60L (16 gal) | Larger tanks are easier to keep stable |
Important: Always dechlorinate tap water before adding it to the tank. Chlorine and chloramines damage a fish's gills and reduce life expectancy.
Interesting Facts About Harlequin Rasbora
- One of the most popular aquarium fish in the hobby for over 100 years
Species Related to Harlequin Rasbora
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Editorial review
This species profile was reviewed for biological accuracy and practical aquarium care guidance. For suspected illness or disease, test your water parameters first and consult an aquatic veterinarian if symptoms persist.