Angelfish and Koi Compatibility Overview
Short answer: No. Angelfish needs 74-84°F and Koi needs 50-75°F. Keep them in separate tanks, or pick one of the safer tank mates listed below.
Angelfish and Koi are generally not recommended to be housed together. Koi is a cool-water fish and Angelfish is tropical, so the usable temperature range decides this pairing. The adult size gap creates a meaningful predation risk. Review the behavior and water details before deciding whether to attempt the pairing.
| 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. Koi is a cool-water fish and Angelfish is tropical, so the usable temperature range decides this pairing. The adult size gap creates a meaningful predation risk. Review the behavior and water details before deciding whether to attempt the pairing.
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) — inside Angelfish's 74–84°F and Koi's 50–75°F.
Is a Angelfish aggressive toward a Koi?
The adult size gap creates a meaningful predation risk.
Safer Tank Mates for Angelfish and Koi
The highest-scoring compatible partners for each species in our compatibility data.
For Angelfish
- Silver Dollar — 90/100
- African Butterfly Fish — 89/100
- Bolivian Ram — 89/100
- Congo Tetra — 88/100
- Moonlight Gourami — 88/100
For Koi
- Weather Loach — 87/100
- Goldfish — 86/100
Related Compatibility Guides
Tank Size for Angelfish and Koi
Use the scenario that matches the actual group sizes and temperament you plan to keep.
| Scenario | Tank | When it applies |
|---|---|---|
| Minimum viable | 100 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 150 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 180 gal | Best when keeping larger schools or reducing territorial pressure. |