Compatibility Overview
Black Phantom 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 | Black Phantom Tetra | Harlequin Rasbora | Verdict |
|---|---|---|---|
| Temperature | 72–82°F | 72–81°F | ✅ 72–81°F |
| pH Range | 6.0–7.0 | 5.5–7.5 | ✅ 6.0–7.0 |
| Temperament | semi | peaceful | ⚠️ Monitor |
| Adult Size | 2.0 in | 1.75 in | ✅ Similar |
| Min. Group | 1+ | 8+ | See below |
| Min. Tank Size | 40 gallons (for both species) | — | |
✅ Compatibility Positives
⚠️ Caution Points
Species Profiles
Black Phantom Tetra — Aquarium species
The Black Phantom Tetra is a popular freshwater fish known for its striking black and silver coloration. It is generally peaceful and can be kept in a community tank with other non-aggressive species. They require a well-maintained tank with a moderate water flow and a good cover of plants. These tetras are suitable for beginners due to their hardiness and e
→ Full Black Phantom Tetra care guide
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 Black Phantom Tetra live with Harlequin Rasbora?
Yes, in a well-planned setup. Black Phantom 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 Black Phantom Tetra and Harlequin Rasbora together?
A minimum of 40 gallons is recommended for keeping Black Phantom Tetra and Harlequin Rasbora together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Black Phantom Tetra and Harlequin Rasbora?
72–81°F
Is a Black Phantom Tetra aggressive toward a Harlequin Rasbora?
Black Phantom Tetra is semi 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 | 75/100 |
| Adult Size | 100/100 |
| Swim Zone | 68/100 |
| Social Needs | 92/100 |
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. |