Compatibility Overview
Molly and Pygmy Corydoras can potentially coexist, but the combination requires careful attention. Some combination of water parameter differences, size mismatch, or temperament issues make this pair challenging. A larger tank (minimum 55 gallons), dense planting, and close monitoring are essential.
| Factor | Molly | Pygmy Corydoras | Verdict |
|---|---|---|---|
| Temperature | 72–82°F | 72–79°F | ✅ 72–79°F |
| pH Range | 7.5–8.5 | 6.0–7.5 | ⚠️ 7.5–7.5 (narrow) |
| Temperament | peaceful | peaceful | ✅ Compatible |
| Adult Size | 4 in | 1 in | ❌ 4× difference |
| Min. Group | 3+ | 6+ | See below |
| Min. Tank Size | 55 gallons (for both species) | — | |
✅ Compatibility Positives
⚠️ Caution Points
Species Profiles
Molly — Poecilia sphenops
Hardy livebearers that prefer alkaline, hard water — sometimes slightly brackish. Prolific breeders; peaceful community fish.
Pygmy Corydoras — Corydoras pygmaeus
Tiny armoured catfish that school in open water as well as on the substrate. Peaceful with all non-aggressive species.
Frequently Asked Questions
Can Molly live with Pygmy Corydoras?
With significant caution and a larger tank. Molly and Pygmy Corydoras can potentially coexist, but the combination requires careful attention. Some combination of water parameter differences, size mismatch, or temperament issues make this pair challenging. A larger tank (minimum 55 gallons), dense planting, and close monitoring are essential.
What tank size do I need for Molly and Pygmy Corydoras together?
A minimum of 55 gallons is recommended for keeping Molly and Pygmy Corydoras together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Molly and Pygmy Corydoras?
72–79°F
Is a Molly aggressive toward a Pygmy Corydoras?
Molly is peaceful and Pygmy Corydoras is peaceful. pH ranges barely or do not overlap: Molly prefers 7.5–8.5; Pygmy Corydoras prefers 6.0–7.5.