Compatibility Overview
Flame Angelfish and Harlequin Rasbora are generally not recommended to be housed together. The issues listed above — whether water parameter incompatibility, predation risk, or aggression — create conditions where one or both fish are likely to suffer harm or chronic stress.
| Factor | Flame Angelfish | Harlequin Rasbora | Verdict |
|---|---|---|---|
| Temperature | 75–81°F | 72–81°F | ✅ 75–81°F |
| pH Range | 8.0–8.3 | 5.5–7.5 | ❌ No overlap |
| Temperament | semi | peaceful | ⚠️ Monitor |
| Adult Size | 2.8 in | 1.75 in | ✅ Similar |
| Min. Group | 1+ | 8+ | See below |
| Min. Tank Size | 55 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
Species Profiles
Flame Angelfish — Aquarium species
The Flame Angelfish is a popular choice for saltwater aquariums due to its vibrant coloration and peaceful nature. It requires a spacious tank with plenty of swimming space and a stable water environment. With proper care, it can thrive in a community tank with compatible species.
→ Full Flame Angelfish 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 Flame Angelfish live with Harlequin Rasbora?
Generally not recommended. Flame Angelfish and Harlequin Rasbora are generally not recommended to be housed together. The issues listed above — whether water parameter incompatibility, predation risk, or aggression — create conditions where one or both fish are likely to suffer harm or chronic stress.
What tank size do I need for Flame Angelfish and Harlequin Rasbora together?
A minimum of 55 gallons is recommended for keeping Flame Angelfish and Harlequin Rasbora together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Flame Angelfish and Harlequin Rasbora?
75–81°F
Is a Flame Angelfish aggressive toward a Harlequin Rasbora?
Flame Angelfish is semi and Harlequin Rasbora is peaceful. These animals require different water types and cannot share one aquarium.
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 | 0/100 |
| 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 | 55 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 75 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 125 gal | Best when keeping larger schools or reducing territorial pressure. |