Compatibility Overview
Congo Tetra and Harlequin Rasbora can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges, and neither poses a major aggression risk to the other. A minimum 40-gallon tank is recommended to provide adequate territory and water volume for both species.
| Factor | Congo Tetra | Harlequin Rasbora | Verdict |
|---|---|---|---|
| Temperature | 72–79°F | 72–81°F | ✅ 72–79°F |
| pH Range | 6.0–7.0 | 5.5–7.5 | ✅ 6.0–7.0 |
| Temperament | aggressive | peaceful | ❌ Risk |
| Adult Size | 1.6 in | 1.75 in | ✅ Similar |
| Min. Group | 6+ | 8+ | See below |
| Min. Tank Size | 40 gallons (for both species) | — | |
✅ Compatibility Positives
⚠️ Caution Points
Species Profiles
Congo Tetra — Aquarium species
The Congo Tetra is a vibrant and active fish that thrives in a well-maintained freshwater aquarium. With its striking coloration and peaceful nature, it's a great addition to any community tank. This species is best kept in groups and requires a spacious tank with plenty of swimming space. They are known for their playful nature and can be seen darting aroun
Harlequin Rasbora — Trigonostigma heteromorpha
Active mid-level schooling fish with a distinctive black triangular patch. One of the best all-around community tank fish.
Frequently Asked Questions
Can Congo Tetra live with Harlequin Rasbora?
Yes, in a well-planned setup. Congo Tetra and Harlequin Rasbora can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges, and neither poses a major aggression risk to the other. A minimum 40-gallon tank is recommended to provide adequate territory and water volume for both species.
What tank size do I need for Congo Tetra and Harlequin Rasbora together?
A minimum of 40 gallons is recommended for keeping Congo Tetra and Harlequin Rasbora together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Congo Tetra and Harlequin Rasbora?
72–79°F
Is a Congo Tetra aggressive toward a Harlequin Rasbora?
Congo Tetra is aggressive and Harlequin Rasbora is peaceful. No major aggression issues are expected between these species.
Related Compatibility Guides
Compatibility score breakdown
The overall score is weighted across water chemistry, behavior, adult size, swimming zone, and social needs. A score is a planning aid—not a guarantee for individual fish.
| Factor | Score |
|---|---|
| Temperature | 100/100 |
| Ph | 100/100 |
| Temperament | 30/100 |
| Adult Size | 100/100 |
| Swim Zone | 68/100 |
| Social Needs | 85/100 |
Tank size scenarios
Use the scenario that matches the actual group sizes and temperament you plan to keep.
| Scenario | Tank | When it applies |
|---|---|---|
| Minimum viable | 40 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 55 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 90 gal | Best when keeping larger schools or reducing territorial pressure. |