Compatibility Overview
Molly and Moonlight Gourami 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 | Moonlight Gourami | Verdict |
|---|---|---|---|
| Temperature | 72–82°F | 72–82°F | ✅ 72–82°F |
| pH Range | 7.5–8.5 | 6.5–7.5 | ⚠️ 7.5–7.5 (narrow) |
| Temperament | peaceful | semi | ⚠️ Monitor |
| Adult Size | 4 in | 2.0 in | ⚠️ 2.0× difference |
| Min. Group | 3+ | 1+ | 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.
Moonlight Gourami — Aquarium species
The Moonlight Gourami is a beautiful freshwater fish known for its silvery blue color and red eyes. It is a peaceful community fish suitable for beginners and can thrive in a well-maintained aquarium. These fish are sensitive to water quality and require a spacious tank with plenty of swimming space. They are not known to school and prefer to have their terr
Frequently Asked Questions
Can Molly live with Moonlight Gourami?
With significant caution and a larger tank. Molly and Moonlight Gourami 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 Moonlight Gourami together?
A minimum of 55 gallons is recommended for keeping Molly and Moonlight Gourami together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Molly and Moonlight Gourami?
72–82°F
Is a Molly aggressive toward a Moonlight Gourami?
Molly is peaceful and Moonlight Gourami is semi. 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 | 72/100 |
| Swim Zone | 68/100 |
| Social Needs | 92/100 |
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. |