Compatibility Overview
Betta Fish and Molly can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges, and neither poses a major aggression risk to the other. A minimum 55-gallon tank is recommended to provide adequate territory and water volume for both species.
| Factor | Betta Fish | Molly | Verdict |
|---|---|---|---|
| Temperature | 76–82°F | 72–82°F | ✅ 76–82°F |
| pH Range | 6.5–7.5 | 7.5–8.5 | ⚠️ 7.5–7.5 (narrow) |
| Temperament | aggressive | peaceful | ❌ Risk |
| Adult Size | 3 in | 4 in | ✅ Similar |
| Min. Group | 1+ | 3+ | See below |
| Min. Tank Size | 55 gallons (for both species) | — | |
✅ Compatibility Positives
⚠️ Caution Points
Species Profiles
Betta Fish — Betta splendens
Vibrant labyrinth fish from Southeast Asia. Males are highly territorial toward other bettas and fin-nippers; compatible with many peaceful species in large, planted tanks.
Molly — Poecilia sphenops
Hardy livebearers that prefer alkaline, hard water — sometimes slightly brackish. Prolific breeders; peaceful community fish.
Frequently Asked Questions
Can Betta Fish live with Molly?
Yes, in a well-planned setup. Betta Fish and Molly can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges, and neither poses a major aggression risk to the other. A minimum 55-gallon tank is recommended to provide adequate territory and water volume for both species.
What tank size do I need for Betta Fish and Molly together?
A minimum of 55 gallons is recommended for keeping Betta Fish and Molly together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Betta Fish and Molly?
76–82°F
Is a Betta Fish aggressive toward a Molly?
Betta Fish is aggressive and Molly is peaceful. pH ranges barely or do not overlap: Betta Fish prefers 6.5–7.5; Molly prefers 7.5–8.5.