Koi can also identify the humans who feed them. Eventually, they build an association between a person standing near the pond and food. This can cause koi to come to the surface when someone walks up to the pond. They don’t do this with everybody, but they are more likely to react most to people they encounter frequently.

Some koi can even be taught to eat out of your hand. Usually this consists of hand feeding them for sucessive days while they get used to you. It requires patience, but many koi will come to eat pellets or other food from an outstretched hand without reservation. It is a quicker process in koi that is brought up in an environment where people regularly feed them.

It's also not unusual for koi to play follow the leader along the side of the pond with someone walking alongside the pond. They can also shift in the same direction and hang around the spot where the person is standing. This behaviour is associated with their conditioning to associate humans with food. When feeding takes place regularly in one location, koi will tend to congregate in that vicinity whenever a person presents. Koi are generally not aggressive, and it is common for them to share the pond environment with other fish. For this reason nothing will drive them away or make them hide when you feed them by hand, or if you stand close by the pond.