Discus and Molly Compatibility Overview
Discus and Molly can potentially coexist, but the combination requires careful attention. Their ranges meet only at 82โ82ยฐF, which leaves no margin for a heater drifting or a warm room. Their pH ranges do not meet: Discus wants 5.0โ7.0 and Molly wants 7.5โ8.5. A larger tank (minimum 100 gallons), dense planting, and close monitoring are essential.
| Factor | Discus | Molly | Verdict |
|---|---|---|---|
| Temperature | 82โ88ยฐF | 72โ82ยฐF | โ ๏ธ 82โ82ยฐF (narrow) |
| pH Range | 5.0โ7.0 | 7.5โ8.5 | โ No overlap |
| Temperament | semi | peaceful | โ ๏ธ Monitor |
| Adult Size | 8 in | 4 in | โ ๏ธ 2.0ร difference |
| Min. Group | 5+ | 3+ | See below |
| Min. Tank Size | 100 gallons (for both species) | โ | |
Compatibility Positives
Caution Points
Species Profiles
Discus โ Symphysodon spp.
The 'king of the aquarium' โ beautiful but demanding. Requires very warm, soft, acidic water that excludes most community 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 Discus live with Molly?
With significant caution and a larger tank. Discus and Molly can potentially coexist, but the combination requires careful attention. Their ranges meet only at 82โ82ยฐF, which leaves no margin for a heater drifting or a warm room. Their pH ranges do not meet: Discus wants 5.0โ7.0 and Molly wants 7.5โ8.5. A larger tank (minimum 100 gallons), dense planting, and close monitoring are essential.
What tank size do I need for Discus and Molly together?
A minimum of 100 gallons is recommended for keeping Discus and Molly together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Discus and Molly?
82โ82ยฐF (narrow) โ inside Discus's 82โ88ยฐF and Molly's 72โ82ยฐF.
Is a Discus aggressive toward a Molly?
Discus is semi and Molly is peaceful. No major aggression issues are expected between these species.
Related Compatibility Guides
Tank Size for Discus and Molly
Use the scenario that matches the actual group sizes and temperament you plan to keep.
| Scenario | Tank | When it applies |
|---|---|---|
| Minimum viable | 100 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 150 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. |