Compatibility Overview
Cardinal 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 | Cardinal Tetra | Swordtail | Verdict |
|---|---|---|---|
| Temperature | 73–82°F | 65–80°F | ✅ 73–80°F |
| pH Range | 4.5–7.0 | 7.0–8.3 | ⚠️ 7.0–7.0 (narrow) |
| Temperament | peaceful | peaceful | ✅ Compatible |
| Adult Size | 1.5 in | 5 in | ⚠️ 3.3× difference |
| Min. Group | 6+ | 3+ | See below |
| Min. Tank Size | 75 gallons (for both species) | — | |
✅ Compatibility Positives
⚠️ Caution Points
Species Profiles
Cardinal Tetra — Paracheirodon axelrodi
Brilliant red-and-blue schooling fish from the Rio Negro. Prefers soft, acidic, warm water — a natural companion for discus.
→ Full Cardinal 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 Cardinal Tetra live with Swordtail?
With significant caution and a larger tank. Cardinal 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 Cardinal Tetra and Swordtail together?
A minimum of 75 gallons is recommended for keeping Cardinal Tetra and Swordtail together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Cardinal Tetra and Swordtail?
73–80°F
Is a Cardinal Tetra aggressive toward a Swordtail?
Cardinal Tetra is peaceful and Swordtail is peaceful. pH ranges barely or do not overlap: Cardinal Tetra prefers 4.5–7.0; Swordtail prefers 7.0–8.3.