Fire Eel and Molly Compatibility Overview
Fire Eel and Molly are generally not recommended to be housed together. The adult size gap creates a meaningful predation risk. Their pH ranges do not meet: Fire Eel wants 6.0โ7.0 and Molly wants 7.5โ8.5. Review the behavior and water details before deciding whether to attempt the pairing.
| Factor | Fire Eel | Molly | Verdict |
|---|---|---|---|
| Temperature | 75โ82ยฐF | 72โ82ยฐF | โ 75โ82ยฐF |
| pH Range | 6.0โ7.0 | 7.5โ8.5 | โ No overlap |
| Temperament | semi | peaceful | โ ๏ธ Monitor |
| Adult Size | 39.4 in | 4 in | โ 10ร difference |
| Min. Group | 1+ | 3+ | See below |
| Min. Tank Size | 100 gallons (for both species) | โ | |
Compatibility Positives
Incompatibility Reasons
Species Profiles
Fire Eel โ Mastacembelus erythrotaenia
The Fire Eel is a stunning, red-bottomed species that requires a spacious tank. They are peaceful bottom feeders and do best in a well-planted, mature aquarium. With a moderate activity level, they can be a great addition to a community tank, but their size and diet may be incompatible with smaller fish.
Molly โ Poecilia sphenops
Hardy livebearers that prefer alkaline, hard water โ sometimes slightly brackish. Prolific breeders; peaceful community fish.
Frequently Asked Questions
Can Fire Eel live with Molly?
Generally not recommended. Fire Eel and Molly are generally not recommended to be housed together. The adult size gap creates a meaningful predation risk. Their pH ranges do not meet: Fire Eel wants 6.0โ7.0 and Molly wants 7.5โ8.5. Review the behavior and water details before deciding whether to attempt the pairing.
What tank size do I need for Fire Eel and Molly together?
A minimum of 100 gallons is recommended for keeping Fire Eel and Molly together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Fire Eel and Molly?
75โ82ยฐF โ inside Fire Eel's 75โ82ยฐF and Molly's 72โ82ยฐF.
Is a Fire Eel aggressive toward a Molly?
The adult size gap creates a meaningful predation risk.
Related Compatibility Guides
Tank Size for Fire Eel and Molly
Use the scenario that matches the actual group sizes and temperament you plan to keep.
| Scenario | Tank | When it applies |
|---|---|---|
| Minimum viable | 114 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 180 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 220 gal | Best when keeping larger schools or reducing territorial pressure. |