Can Jack Dempsey live with Neon Tetra?
High risk due to water mismatch, aggression, or predation.
Why Jack Dempsey and Neon Tetra Don't Make an Easy Pair
The size gap is 8.8" — Jack Dempsey (10.0") and Neon Tetra (1.2"). A fish that fits in another fish's mouth will eventually end up there.
Jack Dempsey
Rocio octofasciata
| Adult Size: | 10.0" |
| Temperament: | aggressive |
| Min Tank: | 55 gal |
| Temperature: | 72-82°F |
| pH Range: | 6.5-8.0 |
Neon Tetra
Paracheirodon innesi
| Adult Size: | 1.2" |
| Temperament: | peaceful |
| Min Tank: | 10 gal |
| Temperature: | 68-77°F |
| pH Range: | 5.5-7.0 |
Water Parameter Overlap
| Parameter | Jack Dempsey | Neon Tetra | Overlap |
|---|---|---|---|
| Temperature | 72-82°F | 68-77°F | 5°F ✓ |
| pH | 6.5-8.0 | 5.5-7.0 | 0.5 ✓ |
Compatibility Breakdown
Temperament Match: aggressive + peaceful. One aggressive → predation/nipping risk.
⚠️ Size Predation Risk: Jack Dempsey (10.0") vs Neon Tetra (1.2"). A 8.8" 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: 45.0/100 (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 77°F.
- pH: maintain 6.5 – 7.0.
- Hiding spots: essential for Neon Tetra — 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
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Accuracy note: This tool uses expert rules + FishBase.org data. Individual fish behavior varies — a aggressive individual Jack Dempsey 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.