Koi are omnivores so they will consume both meat and plant matters. The different types of food that can be offered to koi include vegetables, such as brocolli , spinach, beans, and carrots, as well as live foods. Commercially available food like pellets can also be fed to koi.
Koi aren't picky eaters so their diet is only limited by your imagination. How much they will eat will depend on the water temperatures. So when the weather is cool outside the fall, koi will consume less food than during the hotter months during the summer.