Compatibility Overview
Black Neon Tetra and Swordtail 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 75 gallons), dense planting, and close monitoring are essential.
| Factor | Black Neon Tetra | Swordtail | Verdict |
|---|---|---|---|
| Temperature | 72–82°F | 65–80°F | ✅ 72–80°F |
| pH Range | 6.0–7.0 | 7.0–8.3 | ⚠️ 7.0–7.0 (narrow) |
| Temperament | semi | peaceful | ⚠️ Monitor |
| Adult Size | 0.8 in | 5 in | ❌ 6× difference |
| Min. Group | 6+ | 3+ | See below |
| Min. Tank Size | 75 gallons (for both species) | — | |
✅ Compatibility Positives
⚠️ Caution Points
Species Profiles
Black Neon Tetra — Aquarium species
The Black Neon Tetra is a popular freshwater species known for its vibrant colors and peaceful temperament. It is an excellent addition to community tanks, thriving in groups of 6 or more. These tetras require a well-maintained aquarium with a flowing current and plenty of swimming space. With proper care, they can live up to 5 years. They are adaptable to v
→ Full Black Neon Tetra care guide
Swordtail — Xiphophorus hellerii
Hardy livebearer with a distinctive elongated lower tail fin in males. Peaceful community fish that tolerate a wide temperature range.
Frequently Asked Questions
Can Black Neon Tetra live with Swordtail?
With significant caution and a larger tank. Black Neon Tetra and Swordtail 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 75 gallons), dense planting, and close monitoring are essential.
What tank size do I need for Black Neon Tetra and Swordtail together?
A minimum of 75 gallons is recommended for keeping Black Neon Tetra and Swordtail together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Black Neon Tetra and Swordtail?
72–80°F
Is a Black Neon Tetra aggressive toward a Swordtail?
Black Neon Tetra is semi and Swordtail 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 | 80/100 |
| Ph | 0/100 |
| Temperament | 75/100 |
| Adult Size | 8/100 |
| Swim Zone | 68/100 |
| 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 | 75 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 125 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 150 gal | Best when keeping larger schools or reducing territorial pressure. |