Compatibility Overview
Koi and Neon Tetra are generally not recommended to be housed together. The issues listed above — whether water parameter incompatibility, predation risk, or aggression — create conditions where one or both fish are likely to suffer harm or chronic stress.
| Factor | Koi | Neon Tetra | Verdict |
|---|---|---|---|
| Temperature | 50–75°F | 72–80°F | ⚠️ 72–75°F (narrow) |
| pH Range | 7.0–8.5 | 6.0–7.5 | ⚠️ 7.0–7.5 (narrow) |
| Temperament | peaceful | peaceful | ✅ Compatible |
| Adult Size | 24 in | 1.5 in | ❌ 16× difference |
| Min. Group | 2+ | 6+ | See below |
| Min. Tank Size | 100 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
Species Profiles
Koi — Cyprinus rubrofuscus
Large pond fish that require hundreds of gallons and cool water. Will eat any fish small enough to fit in their mouth.
Neon Tetra — Paracheirodon innesi
Iconic schooling fish with vivid electric-blue and red stripes. Hardy in captivity; suitable for most peaceful community setups.
Frequently Asked Questions
Can Koi live with Neon Tetra?
Generally not recommended. Koi and Neon Tetra are generally not recommended to be housed together. The issues listed above — whether water parameter incompatibility, predation risk, or aggression — create conditions where one or both fish are likely to suffer harm or chronic stress.
What tank size do I need for Koi and Neon Tetra together?
A minimum of 100 gallons is recommended for keeping Koi and Neon Tetra together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Koi and Neon Tetra?
72–75°F (narrow)
Is a Koi aggressive toward a Neon Tetra?
Koi is peaceful and Neon Tetra is peaceful. Koi requires cold water; Neon Tetra requires tropical water. These environments are incompatible.