Hillstream Loach and Koi Compatibility Overview
Hillstream Loach and Koi are generally not recommended to be housed together. Koi is a cool-water fish and Hillstream Loach is tropical, so the usable temperature range decides this pairing. The adult size gap creates a meaningful predation risk. Review the behavior and water details before deciding whether to attempt the pairing.
| Factor | Hillstream Loach | Koi | Verdict |
|---|---|---|---|
| Temperature | 68โ75ยฐF | 50โ75ยฐF | โ 68โ75ยฐF |
| pH Range | 6.0โ7.5 | 7.0โ8.5 | โ ๏ธ 7.0โ7.5 (narrow) |
| Temperament | peaceful | peaceful | โ Compatible |
| Adult Size | 2.6 in | 24 in | โ 9ร difference |
| Min. Group | 4+ | 2+ | See below |
| Min. Tank Size | 100 gallons (for both species) | โ | |
Compatibility Positives
Incompatibility Reasons
Species Profiles
Hillstream Loach โ Sewellia lineolata
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.
โ Full Hillstream Loach care guide
Koi โ Cyprinus rubrofuscus
Large pond fish that require hundreds of gallons and cool water. Will eat any fish small enough to fit in their mouth.
Frequently Asked Questions
Can Hillstream Loach live with Koi?
Generally not recommended. Hillstream Loach and Koi are generally not recommended to be housed together. Koi is a cool-water fish and Hillstream Loach is tropical, so the usable temperature range decides this pairing. The adult size gap creates a meaningful predation risk. Review the behavior and water details before deciding whether to attempt the pairing.
What tank size do I need for Hillstream Loach and Koi together?
A minimum of 100 gallons is recommended for keeping Hillstream Loach and Koi together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Hillstream Loach and Koi?
68โ75ยฐF โ inside Hillstream Loach's 68โ75ยฐF and Koi's 50โ75ยฐF.
Is a Hillstream Loach aggressive toward a Koi?
The adult size gap creates a meaningful predation risk.
Related Compatibility Guides
Tank Size for Hillstream Loach and Koi
Use the scenario that matches the actual group sizes and temperament you plan to keep.
| Scenario | Tank | When it applies |
|---|---|---|
| Minimum viable | 100 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 150 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 220 gal | Best when keeping larger schools or reducing territorial pressure. |