Compatibility Overview
Cardinal Tetra and Rainbow Shark 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 | Rainbow Shark | Verdict |
|---|---|---|---|
| Temperature | 73–82°F | 72–79°F | ✅ 73–79°F |
| pH Range | 4.5–7.0 | 6.5–7.5 | ⚠️ 6.5–7.0 (narrow) |
| Temperament | peaceful | semi | ⚠️ Monitor |
| Adult Size | 1.5 in | 6 in | ❌ 4× difference |
| Min. Group | 6+ | 1+ | 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
Rainbow Shark — Epalzeorhynchos frenatum
Active bottom dweller that becomes territorial at maturity. One per tank; avoid other shark-like or bottom-dwelling species.
Frequently Asked Questions
Can Cardinal Tetra live with Rainbow Shark?
With significant caution and a larger tank. Cardinal Tetra and Rainbow Shark 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 Rainbow Shark together?
A minimum of 75 gallons is recommended for keeping Cardinal Tetra and Rainbow Shark together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Cardinal Tetra and Rainbow Shark?
73–79°F
Is a Cardinal Tetra aggressive toward a Rainbow Shark?
Cardinal Tetra is peaceful and Rainbow Shark is semi. Limited pH overlap (6.5–7.0) — maintain pH carefully within this narrow window.