Koi Feeding: Schedule, Diet, and Why They Stop Eating

Koi feeding runs on water temperature, not the calendar, and getting that wrong in either direction can hurt them. Here's the seasonal schedule and how to read a koi that's stopped eating.

Feeding Schedule by Water Temperature

• Below about 48 to 50°F: Stop feeding entirely. Koi enter torpor, a hibernation-like dormant state, and digestion effectively shuts down. They live off stored body fat until spring.
• 50 to 59°F: Feed sparingly, at most once or twice a day, wheat-germ-based cold-water food only, ideally in the warmest part of the day. Some sources narrow this further to just 2 to 3 times a week in the lower part of this range.
• 59 to 68°F: Once or twice a day. Digestive capacity is declining, watch activity and cut back if fish seem sluggish.
• 68 to 86°F, the optimal growth range: 2 to 4 feedings a day, up to 4 to 6 times daily on very active systems per one manufacturer.
• Above 86 to 90°F: Cut back to 1 to 2 smaller, easily digested feedings, and stop above roughly 90°F, heat stress impairs digestion too.

The traditional 5-minute rule, only offer what's visibly cleaned up in 3 to 5 minutes, is the most widely repeated portion guidance, though at least one koi-specific source argues keepers who rely on it tend to overfeed by a wide margin, that specific figure wasn't corroborated elsewhere. A body-weight-based alternative, roughly 1 to 4% of body weight a day depending on temperature and size, is worth using if you want more precision. Baby and juvenile koi tolerate warm water and frequent feeding better than adults, and can often be fed up to 4 times a day even at summer's highest temperatures.

What Koi Eat

The staple is commercial floating koi pellets, switched seasonally by protein content. A warm-season growth and color formula, used once water is consistently above roughly 60 to 64°F, runs 32 to 40%+ crude protein, primarily fish meal and krill meal, often with spirulina and color-enhancing additives. A cool-season wheat-germ formula for spring and fall runs lower protein, roughly 25 to 32%, and is easier to digest at low metabolic rates.

Supplement 2 to 3 times a week with treats, not a daily staple: fruit like watermelon, orange segments, banana, and berries with seeds and rind removed, vegetables like lettuce and spinach fed raw or cooked broccoli, and protein treats like brine shrimp, daphnia, bloodworms, mealworms, earthworms, or small amounts of unseasoned cooked chicken. Blanch or chop produce into bite-size pieces rather than feeding it whole.

Safe Treats and Foods to Avoid

Safe, in moderation: watermelon, orange segments, banana, berries, melon, lettuce, spinach, cooked broccoli, brine shrimp, daphnia, bloodworms, mealworms, earthworms, and small bits of unseasoned cooked chicken. Peas are a genuine point of disagreement, some sources call them a top treat, others say only in small, thoroughly cooked amounts, hard or dried peas are a real choking and blockage risk, so cook and shell them if you feed them at all.

Avoid: bread and other processed human snacks, low in nutrients and can pollute pond water, cat or dog food, koi aren't equipped to digest animal fats well, and corn, especially hard or dried, which is difficult to digest and a blockage risk. Always remove fruit seeds, pits, and citrus rind before feeding.

Why Koi Stop Eating

1. Cold water torpor. Below roughly 48 to 50°F, koi enter a hibernation-like dormant state and stop eating entirely. This is the single most common, entirely expected reason a koi goes off food every year.
2. Poor water quality. Ammonia or nitrite spikes, pH swings, or overcrowding stress koi and suppress appetite. If multiple fish stop eating at once, that's a signal to test water immediately rather than assume a benign cause.
3. Stress. A new pond, predator visits, loud noise or vibration near the pond, netting, or transport can suppress feeding, generally short-term.
4. Spawning. Around and after the spawning chase, typically in the mid-60s to mid-70s°F, appetite can dip, especially in females, who reportedly take longer to recover than males.
5. Parasites or bacterial infection. A stress-weakened immune system opens the door to gill flukes and bacterial infections, commonly presenting as reduced appetite alongside other symptoms.
6. Koi herpesvirus. A serious, notifiable viral disease with lethargy, appetite loss, gasping near aerators, and skin changes as symptoms. Outbreaks are worst in the 61 to 77°F range, mortality is commonly cited at 70 to 100%, and there's no available treatment.
7. Diet monotony. Koi can become disinterested in stale or low-quality feed. Varying treats and food brands is the suggested fix.

When to Worry

Context matters a lot here. In winter, going weeks to months without eating is by design and not a red flag by itself. In warm water, koi can go roughly two weeks without dedicated feeding since they forage naturally on algae and insects in the pond, so a few days of reduced eating isn't automatically an emergency.

Genuine warning signs: multiple fish, not just one, refusing food simultaneously with no temperature explanation, appetite loss persisting beyond a few days in warm water, or refusal paired with sluggish movement, color loss, visible sores or ulcers, hiding behavior, sunken eyes, rough or discolored skin, gasping at the surface, or a suddenly thin body. One source suggests contacting a koi veterinarian if appetite loss persists beyond 48 hours, though that specific number wasn't corroborated elsewhere, treat it as a reasonable guideline rather than an established standard. Weight loss combined with lethargy is consistently flagged as a reason to involve a vet.

Sources & Further Reading