Choosing Koi Tank Mates
Good Koi tank mates share the same temperature and pH window, will not be eaten by (or eat) the Koi, and do not compete for the same swimming zone or feeding time. Each pair guide below scores those factors from 0 to 100 and gives the minimum tank size for keeping both species together.
Start with the highest-scoring pairs; anything under 45 is listed so you know what to avoid, not as a recommendation.
Care baseline
Large pond fish that require hundreds of gallons and cool water. Will eat any fish small enough to fit in their mouth.
| Temperature | 50–75°F |
| pH | 7.0–8.5 |
| Adult size | 24 in |
| Minimum group | 2 |