Can Goldfish Safely Coexist With Koi Fish?

When it comes to different species of fish coexisting together in the same environment, the usual rule of thumb is that the larger fish will eat their smaller counterparts. However, this is not necessarily the case with koi and goldfish. The two can peacefully coexist in the same pond or aquarium, so long as strict policies are followed, which are highlighted below.

Goldfish And Koi Have A Lot In Common

Both of these fish are members of the family Cyprinidae. As such, they prefer similar water temperatures, filters and care requirements. However, koi can grow significantly larger than goldfish, and this must be taken into consideration when placing them in the same pond. Generally speaking, it is best to only place goldfish into koi ponds that are large enough to deter the koi from attempting to consume them.

Both koi and goldfish will eat anything that is small enough for them to swallow, and this includes other species of fish. In the wild, it is a necessary adaptation that gives them the ability to survive even in environments where food is scarce, but for obvious reasons this is undesirable in a backyard pond. Those who choose to place goldfish in the same pond as koi will need to protect them until they become large enough to deter the koi from attempting to prey on them. The reverse is also true; koi fry are vulnerable to being eaten by goldfish since they are very small. The good news is that koi offspring grow rapidly and in about one or two months will be large enough for goldfish to avoid.

Keep The Goldfish In Holding Tanks Until They Are Larger

Prior to introducing new fish to your pond they should be placed in quarantine and monitored to ensure they are not diseased. Even if they are clean, it is a good idea to wait until they are large enough to be placed in close proximity to koi. The good news is that both koi and goldfish have affable personalities. Neither species is aggressive and as such will not attack each other. It is for this reason that many enthusiasts consider them the perfect pond mates.

New koi, especially those that are young, will also need to be placed in quarantine and holding tanks prior to introducing them to the pond, but this should only be done for a set period of time. Koi can grow to be over 2 feet long and as a consequence holding them long term in a tank requires special equipment and resources which are beyond the scope of most pond owners.

Once your young koi reach a length of about six inches, they should be moved to the pond where they will have more space. At this point no goldfish will bother them. While the goldfish or koi are still in the holding tank, be sure to place substrate near the bottom, since both of these fish are bottom feeders and the substrate will provide them with an opportunity to munch.