Compatibility Overview
Molly and Otocinclus 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 | Molly | Otocinclus | Verdict |
|---|---|---|---|
| Temperature | 72–82°F | 72–82°F | ✅ 72–82°F |
| pH Range | 7.5–8.5 | 6.0–7.5 | ⚠️ 7.5–7.5 (narrow) |
| Temperament | peaceful | peaceful | ✅ Compatible |
| Adult Size | 4 in | 1.5 in | ⚠️ 2.7× difference |
| Min. Group | 3+ | 4+ | 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.
Otocinclus — Otocinclus spp.
Tiny algae-eating catfish that are peaceful with all species. Need established algae growth and biofilm; sensitive to ammonia.
Frequently Asked Questions
Can Molly live with Otocinclus?
Yes, in a well-planned setup. Molly and Otocinclus 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 Molly and Otocinclus together?
A minimum of 55 gallons is recommended for keeping Molly and Otocinclus together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Molly and Otocinclus?
72–82°F
Is a Molly aggressive toward a Otocinclus?
Molly is peaceful and Otocinclus is peaceful. pH ranges barely or do not overlap: Molly prefers 7.5–8.5; Otocinclus prefers 6.0–7.5.