Compatibility Overview
Guppy and Hillstream 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 29 gallons), dense planting, and close monitoring are essential.
| Factor | Guppy | Hillstream Loach | Verdict |
|---|---|---|---|
| Temperature | 72–82°F | 64–73°F | ⚠️ 72–73°F (narrow) |
| pH Range | 6.8–8.5 | 6.5–7.5 | ⚠️ 6.8–7.5 (narrow) |
| Temperament | peaceful | semi | ⚠️ Monitor |
| Adult Size | 2.5 in | 2.0 in | ✅ Similar |
| Min. Group | 3+ | 1+ | See below |
| Min. Tank Size | 29 gallons (for both species) | — | |
✅ Compatibility Positives
⚠️ Caution Points
Species Profiles
Guppy — Poecilia reticulata
Hardy and colourful livebearers. Males' long flowing tails make them targets for fin-nipping species. Very prolific breeders.
Hillstream Loach — Aquarium species
Sewellia lineolata, known as the Hillstream Loach, is a fascinating species for aquarists. These fish require a well-oxygenated, clear water environment with plenty of hiding spots. With a lifespan of 7 years, they are a long-term commitment. Their olive green color and slender body shape add a unique aesthetic to the tank. Despite their moderate activity le
Frequently Asked Questions
Can Guppy live with Hillstream Loach?
With significant caution and a larger tank. Guppy and Hillstream 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 29 gallons), dense planting, and close monitoring are essential.
What tank size do I need for Guppy and Hillstream Loach together?
A minimum of 29 gallons is recommended for keeping Guppy and Hillstream Loach together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Guppy and Hillstream Loach?
72–73°F (narrow)
Is a Guppy aggressive toward a Hillstream Loach?
Guppy is peaceful and Hillstream Loach is semi. 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 | 11/100 |
| Ph | 70/100 |
| Temperament | 75/100 |
| Adult Size | 100/100 |
| 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 | 29 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 40 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 55 gal | Best when keeping larger schools or reducing territorial pressure. |