Can Hillstream Loach live with Rainbow Shark?
High risk due to water mismatch, aggression, or predation.
Why Hillstream Loach and Rainbow Shark Don't Make an Easy Pair
The size gap is 3.5" — Hillstream Loach (2.5") and Rainbow Shark (6.0"). A fish that fits in another fish's mouth will eventually end up there.
Hillstream Loach
Sewellia lineolata
| Adult Size: | 2.5" |
| Temperament: | peaceful |
| Min Tank: | 20 gal |
| Temperature: | 64-75°F |
| pH Range: | 6.5-7.5 |
Rainbow Shark
Epalzeorhynchos frenatum
| Adult Size: | 6.0" |
| Temperament: | semi-aggressive |
| Min Tank: | 55 gal |
| Temperature: | 72-82°F |
| pH Range: | 6.5-7.5 |
Water Parameter Overlap
| Parameter | Hillstream Loach | Rainbow Shark | Overlap |
|---|---|---|---|
| Temperature | 64-75°F | 72-82°F | 3°F ✓ |
| pH | 6.5-7.5 | 6.5-7.5 | 1.0 ✓ |
Compatibility Breakdown
Temperament Match: peaceful + semi-aggressive. Semi-aggressive → watch territory and feeding.
⚠️ Size Predation Risk: Hillstream Loach (2.5") vs Rainbow Shark (6.0"). A 3.5" gap — the larger fish will view the smaller fish as food.
Score: 40.0/100 (GOOD ≥80, CAUTION ≥50, RISKY <50).
🔧 Tank Setup Requirements (for Both)
- Minimum tank: 55 gallons — sized for the larger fish in the pair.
- Temperature: keep it between 72°F and 75°F.
- pH: maintain 6.5 – 7.5.
- Hiding spots: essential for Hillstream Loach — caves, plants, or driftwood to retreat when feeling stressed.
- Water changes: 25% weekly minimum. Two species mean double the bioload.
🔧 Tank Stocking Calculator
Enter tank size to calculate safe stocking levels:
Recommended Equipment
Based on tank size 55+ gallons:
High-quality freshwater flake food
Explore Related Checks
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Accuracy note: This tool uses expert rules + FishBase.org data. Individual fish behavior varies — a peaceful individual Hillstream Loach may act differently from its species average. Always observe, quarantine new arrivals for 2-4 weeks, and avoid overcrowding. If a pairing says CAUTION, start with a smaller group and a lid.