Compatibility Overview
Angelfish and Koi 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 | Angelfish | Koi | Verdict |
|---|---|---|---|
| Temperature | 74–84°F | 50–75°F | ⚠️ 74–75°F (narrow) |
| pH Range | 6.0–7.5 | 7.0–8.5 | ⚠️ 7.0–7.5 (narrow) |
| Temperament | semi | peaceful | ⚠️ Monitor |
| Adult Size | 6 in | 24 in | ❌ 4× difference |
| Min. Group | 1+ | 2+ | See below |
| Min. Tank Size | 100 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
Species Profiles
Angelfish — Pterophyllum scalare
Elegant South American cichlids with long flowing fins. Generally peaceful but territorial when breeding and will eat very small fish.
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.
Frequently Asked Questions
Can Angelfish live with Koi?
Generally not recommended. Angelfish and Koi 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 Angelfish and Koi together?
A minimum of 100 gallons is recommended for keeping Angelfish and Koi together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Angelfish and Koi?
74–75°F (narrow)
Is a Angelfish aggressive toward a Koi?
Angelfish is semi and Koi is peaceful. Angelfish requires tropical water; Koi requires cold water. These environments are incompatible.