Can Betta Fish live with Lyretail Killifish?
Case-by-case. Watch group sizes, tank size, and feeding zones.
Why Betta Fish and Lyretail Killifish Don't Make an Easy Pair
They can coexist, but you need to manage the setup carefully. The temperature margin is tight — only 2°F of safe overlap, which leaves little room for thermostat drift.
Betta Fish
Betta splendens
| Adult Size: | 2.8" |
| Temperament: | semi-aggressive |
| Min Tank: | 5 gal |
| Temperature: | 75-80°F |
| pH Range: | 6.5-7.5 |
Lyretail Killifish
Aphyosemion australe
| Adult Size: | 2.5" |
| Temperament: | peaceful |
| Min Tank: | 10 gal |
| Temperature: | 72-77°F |
| pH Range: | 6.0-7.0 |
Water Parameter Overlap
| Parameter | Betta Fish | Lyretail Killifish | Overlap |
|---|---|---|---|
| Temperature | 75-80°F | 72-77°F | 2°F ✓ |
| pH | 6.5-7.5 | 6.0-7.0 | 0.5 ✓ |
Compatibility Breakdown
Temperament Match: semi-aggressive + peaceful. Semi-aggressive → watch territory and feeding.
Score: 50.0/100 (GOOD ≥80, CAUTION ≥50, RISKY <50).
🔧 Tank Setup Requirements (for Both)
- Minimum tank: 10 gallons — sized for the larger fish in the pair.
- Temperature: keep it between 75°F and 77°F.
- pH: maintain 6.5 – 7.0.
- Hiding spots: essential for Betta Fish — 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 10+ gallons:
Frozen bloodworms for carnivorous killifish
Explore Related Checks
See what else works with these fish:
⚠️ Common Reasons This Pairing Fails in Practice
- Narrow temperature margin: Only 2°F of overlap means a stuck heater or seasonal temperature swing can push one species out of its comfort zone.
- Overcrowding: Even compatible species fail in tanks that are too small. Double the species means double the bioload — 25% weekly water changes are the minimum.
- Inadequate acclimation: Adding both species on the same day without quarantine is a common mistake. Always drip-acclimate new arrivals and quarantine for 2–4 weeks.
Tools & Resources
Accuracy note: This tool uses expert rules + FishBase.org data. Individual fish behavior varies — a semi-aggressive individual Betta Fish 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.