What Do Koi Fish Eat? Diet, Feeding, and What to Avoid

Koi are omnivores with the appetite of a labrador: they’ll eat almost anything, which is exactly why what you choose to feed matters.

The staple: a quality pellet

The core of a pond koi’s diet should be a formulated pellet or stick matched to the season — higher protein (35–40%) in summer for growth, wheat-germ-based and easier to digest in spring and fall when metabolism slows. Feed only what the fish clear in about five minutes; uneaten food becomes ammonia. Our koi food guide compares the types in depth.

Treats koi genuinely benefit from

• Vegetables: lettuce, peas (shelled), spinach, watermelon — floated in small pieces
• Proteins: earthworms, silkworm pupae, freeze-dried shrimp — classic conditioning foods before shows or breeding
• Fruit: orange slices are a summer favorite and a vitamin C source

Treats also do the thing hobbyists love most: hand-feeding. Docile varieties like Chagoi usually learn first and teach the rest of the pond.

What to never feed

Bread, chips, and anything processed (swells, no nutrition, fouls water); rice and pasta (same); anything caught wild that might carry parasites. If you feed from your kitchen, keep it to the produce list above.

Temperature rules everything

Koi are cold-blooded; their digestion runs at the speed of the water:

Water temp	Feeding
Above 68°F	2–4x daily, growth formula
60–68°F	1–2x daily
50–60°F	A few times weekly, wheat-germ formula
Below 50°F	Stop feeding

Feeding in cold water is one of the most common beginner mistakes — the food rots inside the fish. Our winter koi care guide covers the cold-season routine.

Ask your dealer what the fish was raised on

A koi’s early diet shapes its growth and color. Good dealers will tell you exactly what they feed and why — it’s a useful trust signal, and one worth checking alongside the quarantine practices listed on every FindKoi dealer profile. Switching foods? Transition over a week to avoid digestive trouble.