Compatibility Overview
Koi and Peacock Cichlid 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 | Peacock Cichlid | Verdict |
|---|---|---|---|
| Temperature | 50–75°F | 75–81°F | ⚠️ 75–75°F (narrow) |
| pH Range | 7.0–8.5 | 7.5–8.5 | ✅ 7.5–8.5 |
| Temperament | peaceful | aggressive | ❌ Risk |
| Adult Size | 24 in | 3.1 in | ❌ 8× difference |
| Min. Group | 2+ | 1+ | 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.
Peacock Cichlid — Aquarium species
The Peacock Cichlid, Aulonocara nyassae, is a stunning fish with vibrant blue and yellow colors. These fish are known for their aggression and require a mature and well-maintained tank. They are best kept in pairs or in a species-specific tank. Careful attention must be given to water parameters and tank setup to ensure their health and well-being.
Frequently Asked Questions
Can Koi live with Peacock Cichlid?
Generally not recommended. Koi and Peacock Cichlid 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 Peacock Cichlid together?
A minimum of 100 gallons is recommended for keeping Koi and Peacock Cichlid together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Koi and Peacock Cichlid?
75–75°F (narrow)
Is a Koi aggressive toward a Peacock Cichlid?
Koi is peaceful and Peacock Cichlid is aggressive. These animals require different water types and cannot share one aquarium.
Related Compatibility Guides
Compatibility score breakdown
The overall score is weighted across water chemistry, behavior, adult size, swimming zone, and social needs. A score is a planning aid—not a guarantee for individual fish.
| Factor | Score |
|---|---|
| Temperature | 0/100 |
| Ph | 100/100 |
| Temperament | 30/100 |
| Adult Size | 8/100 |
| Swim Zone | 68/100 |
| Social Needs | 92/100 |
Tank size scenarios
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. |