Goldfish and Koi Compatibility Overview
Goldfish and Koi can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges. Both species are peaceful, and neither poses a major aggression risk to the other. A minimum 100-gallon tank is recommended to provide adequate territory and water volume for both species.
| Factor | Goldfish | Koi | Verdict |
|---|---|---|---|
| Temperature | 50โ74ยฐF | 50โ75ยฐF | โ 50โ74ยฐF |
| pH Range | 6.5โ8.0 | 7.0โ8.5 | โ 7.0โ8.0 |
| Temperament | peaceful | peaceful | โ Compatible |
| Adult Size | 12 in | 24 in | โ ๏ธ 2.0ร difference |
| Min. Group | 1+ | 2+ | See below |
| Min. Tank Size | 100 gallons (for both species) | โ | |
Compatibility Positives
Caution Points
Species Profiles
Goldfish โ Carassius auratus
Classic pond and aquarium fish that prefer cool water. Heavy waste producers that require robust filtration. Will eat small fish and shrimp.
Koi โ 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 Goldfish live with Koi?
Yes, in a well-planned setup. Goldfish and Koi can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges. Both species are peaceful, and neither poses a major aggression risk to the other. A minimum 100-gallon tank is recommended to provide adequate territory and water volume for both species.
What tank size do I need for Goldfish and Koi together?
A minimum of 100 gallons is recommended for keeping Goldfish and Koi together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Goldfish and Koi?
50โ74ยฐF โ inside Goldfish's 50โ74ยฐF and Koi's 50โ75ยฐF.
Is a Goldfish aggressive toward a Koi?
Goldfish is peaceful and Koi is peaceful. No major aggression issues are expected between these species.
Related Compatibility Guides
Tank Size for Goldfish 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. |