Koi and most other fish species are not ideal pond mates.
Why?
- Koi are large and powerful, outcompeting smaller fish and potentially injuring them.
- Koi are herbivores, while many other fish are carnivores or omnivores.
- Koi can carry diseases harmful to other fish.
Possible Exceptions
- Some goldfish varieties (comets, shubunkins)
- Large, robust fish like sturgeon or some catfish
- Small, quick fish like minnows or mosquito fish (still risky)
Key Considerations
Pond size, water quality, diet, and temperament all matter. The safest approach is usually a single-species pond or separate ponds for each species.