Compatibility Overview
Glass Catfish 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 | Glass Catfish | Molly | Verdict |
|---|---|---|---|
| Temperature | 72–82°F | 72–82°F | ✅ 72–82°F |
| pH Range | 6.5–7.5 | 7.5–8.5 | ⚠️ 7.5–7.5 (narrow) |
| Temperament | semi | peaceful | ⚠️ Monitor |
| Adult Size | 3.9 in | 4 in | ✅ Similar |
| Min. Group | 6+ | 3+ | See below |
| Min. Tank Size | 55 gallons (for both species) | — | |
✅ Compatibility Positives
⚠️ Caution Points
Species Profiles
Glass Catfish — Aquarium species
The Glass Catfish, Kryptopterus vitreolus, is a popular freshwater aquarium fish known for its unique, translucent body and iridescent scales. It is a peaceful species that thrives in groups and is suitable for beginners due to its hardy nature. These catfish are bottom-dwellers and require a well-decorated tank with plenty of swimming space. They are sensit
→ Full Glass Catfish care guide
Molly — Poecilia sphenops
Hardy livebearers that prefer alkaline, hard water — sometimes slightly brackish. Prolific breeders; peaceful community fish.
Frequently Asked Questions
Can Glass Catfish live with Molly?
Yes, in a well-planned setup. Glass Catfish 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 Glass Catfish and Molly together?
A minimum of 55 gallons is recommended for keeping Glass Catfish and Molly together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Glass Catfish and Molly?
72–82°F
Is a Glass Catfish aggressive toward a Molly?
Glass Catfish is semi and Molly is peaceful. Their preferred pH ranges are difficult to reconcile.
Related Compatibility Guides
Compatibility score breakdown
The overall score is weighted across water chemistry, behavior, adult size, swimming zone, and social needs. A score is a planning aid—not a guarantee for individual fish.
| Factor | Score |
|---|---|
| Temperature | 100/100 |
| Ph | 0/100 |
| Temperament | 75/100 |
| Adult Size | 100/100 |
| Swim Zone | 92/100 |
| Social Needs | 85/100 |
Tank size scenarios
Use the scenario that matches the actual group sizes and temperament you plan to keep.
| Scenario | Tank | When it applies |
|---|---|---|
| Minimum viable | 55 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 75 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 125 gal | Best when keeping larger schools or reducing territorial pressure. |