Compatibility Overview
Hillstream Loach and Swordtail 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 55-gallon tank is recommended to provide adequate territory and water volume for both species.
| Factor | Hillstream Loach | Swordtail | Verdict |
|---|---|---|---|
| Temperature | 64–73°F | 65–80°F | ✅ 65–73°F |
| pH Range | 6.5–7.5 | 7.0–8.3 | ⚠️ 7.0–7.5 (narrow) |
| Temperament | semi | peaceful | ⚠️ Monitor |
| Adult Size | 2.0 in | 5 in | ⚠️ 2.5× difference |
| Min. Group | 1+ | 3+ | See below |
| Min. Tank Size | 55 gallons (for both species) | — | |
✅ Compatibility Positives
⚠️ Caution Points
Species Profiles
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
→ Full Hillstream Loach care guide
Swordtail — Xiphophorus hellerii
Hardy livebearer with a distinctive elongated lower tail fin in males. Peaceful community fish that tolerate a wide temperature range.
Frequently Asked Questions
Can Hillstream Loach live with Swordtail?
Yes, in a well-planned setup. Hillstream Loach and Swordtail 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 55-gallon tank is recommended to provide adequate territory and water volume for both species.
What tank size do I need for Hillstream Loach and Swordtail together?
A minimum of 55 gallons is recommended for keeping Hillstream Loach and Swordtail together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Hillstream Loach and Swordtail?
65–73°F
Is a Hillstream Loach aggressive toward a Swordtail?
Hillstream Loach is semi and Swordtail 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 | 89/100 |
| Ph | 50/100 |
| Temperament | 75/100 |
| 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 | 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. |