Compatibility Overview
Harlequin Rasbora and Weather Loach can potentially coexist, but the combination requires careful attention. Some combination of water parameter differences, size mismatch, or temperament issues make this pair challenging. A larger tank (minimum 75 gallons), dense planting, and close monitoring are essential.
| Factor | Harlequin Rasbora | Weather Loach | Verdict |
|---|---|---|---|
| Temperature | 72–81°F | 59–72°F | ⚠️ 72–72°F (narrow) |
| pH Range | 5.5–7.5 | 6.5–7.5 | ✅ 6.5–7.5 |
| Temperament | peaceful | aggressive | ❌ Risk |
| Adult Size | 1.75 in | 3.9 in | ⚠️ 2.2× difference |
| Min. Group | 8+ | 1+ | See below |
| Min. Tank Size | 75 gallons (for both species) | — | |
✅ Compatibility Positives
⚠️ Caution Points
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
Weather Loach — Aquarium species
The Weather Loach, also known as the Weather Fish, is a popular addition to freshwater aquariums due to its peaceful nature and intriguing behavior. It has a slender, eel-like body with a translucent appearance and dark spots. These loaches are active and enjoy exploring their tank, making them a moderate activity level fish. They do not school and are gener
Frequently Asked Questions
Can Harlequin Rasbora live with Weather Loach?
With significant caution and a larger tank. Harlequin Rasbora and Weather Loach can potentially coexist, but the combination requires careful attention. Some combination of water parameter differences, size mismatch, or temperament issues make this pair challenging. A larger tank (minimum 75 gallons), dense planting, and close monitoring are essential.
What tank size do I need for Harlequin Rasbora and Weather Loach together?
A minimum of 75 gallons is recommended for keeping Harlequin Rasbora and Weather Loach together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Harlequin Rasbora and Weather Loach?
72–72°F (narrow)
Is a Harlequin Rasbora aggressive toward a Weather Loach?
Harlequin Rasbora is peaceful and Weather Loach is aggressive. Their preferred temperature ranges have little or no safe overlap.
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 | 0/100 |
| Ph | 100/100 |
| Temperament | 30/100 |
| Adult Size | 72/100 |
| Swim Zone | 92/100 |
| 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 | 75 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 125 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 150 gal | Best when keeping larger schools or reducing territorial pressure. |