Compatibility Overview
Molly and X Ray Tetra 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 | X Ray Tetra | Verdict |
|---|---|---|---|
| Temperature | 72–82°F | 72–82°F | ✅ 72–82°F |
| pH Range | 7.5–8.5 | 6.0–7.0 | ❌ No overlap |
| Temperament | peaceful | semi | ⚠️ Monitor |
| Adult Size | 4 in | 1.2 in | ⚠️ 3.3× 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.
X Ray Tetra — Aquarium species
The Pristella maxillaris, also known as the X-Ray Tetra, is a popular freshwater fish known for its unique appearance and peaceful nature. They are slender and iridescent, with a clear, almost x-ray-like body. They are best kept in groups of 6 or more and thrive in well-planted tanks with a moderate water flow. Their peaceful temperament makes them ideal for
Frequently Asked Questions
Can Molly live with X Ray Tetra?
With significant caution and a larger tank. Molly and X Ray Tetra 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 X Ray Tetra together?
A minimum of 55 gallons is recommended for keeping Molly and X Ray Tetra together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Molly and X Ray Tetra?
72–82°F
Is a Molly aggressive toward a X Ray Tetra?
Molly is peaceful and X Ray Tetra 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 | 38/100 |
| 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. |