Compatibility Overview
Harlequin Rasbora and Silver Arowana 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 | Harlequin Rasbora | Silver Arowana | Verdict |
|---|---|---|---|
| Temperature | 72–81°F | 72–86°F | ✅ 72–81°F |
| pH Range | 5.5–7.5 | 6.0–7.5 | ✅ 6.0–7.5 |
| Temperament | peaceful | semi | ⚠️ Monitor |
| Adult Size | 1.75 in | 19.7 in | ❌ 11× difference |
| Min. Group | 8+ | 1+ | See below |
| Min. Tank Size | 100 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
Species Profiles
Harlequin Rasbora — Trigonostigma heteromorpha
Active mid-level schooling fish with a distinctive black triangular patch. One of the best all-around community tank fish.
→ Full Harlequin Rasbora care guide
Silver Arowana — Aquarium species
The Silver Arowana is a majestic and unique fish known for its striking appearance and size. It is a large, predatory fish that requires a spacious tank and specific water conditions. While not a community fish, it can be kept with compatible, larger species. They are sensitive to stress and require careful water quality management.
Frequently Asked Questions
Can Harlequin Rasbora live with Silver Arowana?
Generally not recommended. Harlequin Rasbora and Silver Arowana 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 Harlequin Rasbora and Silver Arowana together?
A minimum of 100 gallons is recommended for keeping Harlequin Rasbora and Silver Arowana together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Harlequin Rasbora and Silver Arowana?
72–81°F
Is a Harlequin Rasbora aggressive toward a Silver Arowana?
Harlequin Rasbora is peaceful and Silver Arowana is semi. The adult size gap creates a meaningful predation risk.
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 | 8/100 |
| 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 | 528 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 750 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 950 gal | Best when keeping larger schools or reducing territorial pressure. |