Can Hillstream Loach live with Jack Dempsey?
High risk due to water mismatch, aggression, or predation.
Why Hillstream Loach and Jack Dempsey Don't Make an Easy Pair
The size gap is 7.5" — Hillstream Loach (2.5") and Jack Dempsey (10.0"). 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 |
Jack Dempsey
Rocio octofasciata
| Adult Size: | 10.0" |
| Temperament: | aggressive |
| Min Tank: | 55 gal |
| Temperature: | 72-82°F |
| pH Range: | 6.5-8.0 |
Water Parameter Overlap
| Parameter | Hillstream Loach | Jack Dempsey | Overlap |
|---|---|---|---|
| Temperature | 64-75°F | 72-82°F | 3°F ✓ |
| pH | 6.5-7.5 | 6.5-8.0 | 1.0 ✓ |
Compatibility Breakdown
Temperament Match: peaceful + aggressive. One aggressive → predation/nipping risk.
⚠️ Size Predation Risk: Hillstream Loach (2.5") vs Jack Dempsey (10.0"). A 7.5" gap — the larger fish will view the smaller fish as food.
⚠️ Diet Conflict: A carnivore sharing water with a fish small enough to fit in its mouth is a waiting game. Feed generously, but the risk is structural — not something you can manage meal by meal.
Score: 35.0/100 (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:
Floating pellet for medium to large cichlids
Explore Related Checks
See what else works with these fish:
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.