Can Molly live with Neon Tetra?
Case-by-case. Watch group sizes, tank size, and feeding zones.
Why Molly and Neon Tetra Don't Make an Easy Pair
They can coexist, but you need to manage the setup carefully. The temperament combination (peaceful+peaceful) can work, but you will need to watch them at feeding time for the first week.
Molly
Poecilia sphenops
| Adult Size: | 4.5" |
| Temperament: | peaceful |
| Min Tank: | 20 gal |
| Temperature: | 72-82°F |
| pH Range: | 7.0-8.0 |
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 | Molly | Neon Tetra | Overlap |
|---|---|---|---|
| Temperature | 72-82°F | 68-77°F | 5°F ✓ |
| pH | 7.0-8.0 | 5.5-7.0 | No overlap ✗ |
Compatibility Breakdown
Temperament Match: peaceful + peaceful. Both peaceful → minimal conflict.
⚠️ Size Predation Risk: Molly (4.5") vs Neon Tetra (1.2"). A 3.3" gap — the larger fish will view the smaller fish as food.
Score: 50/100 (GOOD ≥80, CAUTION ≥50, RISKY <50).
🔧 Tank Setup Requirements (for Both)
- Minimum tank: 20 gallons — sized for the larger fish in the pair.
- Temperature: keep it between 72°F and 77°F.
- pH: no shared range. One species will be outside its tolerance regardless of what you set.
- Hiding spots: essential for Molly — 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 20+ gallons:
Quiet internal filter for 20-gallon tanks
Explore Related Checks
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Accuracy note: This tool uses expert rules + FishBase.org data. Individual fish behavior varies — a peaceful individual Molly 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.