Koi food: what to feed and when
Koi food generally comes as floating pellets or sticks, sized and formulated for a fish that can grow considerably larger than typical pond fish, and what you feed needs to change with the season far more than most owners expect. A wheatgerm-based food for cooler water and a higher-protein growth food for the warmer months are the two staples worth knowing about.
Why koi feeding is more seasonal than other pond fish
Koi are cold-blooded, so their metabolism slows right down as pond water cools, which means their ability to digest food properly slows down with it. Feeding a rich, high-protein food when the water is cold can leave undigested food sitting in the gut, which is a genuine welfare problem rather than just a wasted feed.
A wheatgerm-based food is easier to digest at lower temperatures and is the standard choice for spring and autumn, when water is cooling or warming but not yet at a stable summer temperature. Many koi keepers stop feeding altogether once water temperature drops low enough over winter, since the fish's digestion effectively shuts down.
What to look for in a summer food
During the warmer months, when koi are most active and their metabolism is working properly, a higher-protein growth or colour-enhancing food supports the energy they're actually using. Colour-enhancing formulas usually include natural pigments intended to bring out the reds and oranges in a koi's markings, though the effect varies between individual fish.
Floating pellets let you watch how much is actually being eaten and remove anything left after a few minutes, which matters for water quality in a way it doesn't in a fast-flowing river — uneaten food breaks down and affects the pond environment if it's routinely overfed.
How much and how often
Feed only what koi can finish within a few minutes, several small feeds through the day in summer rather than one large feed, which mimics how they'd naturally graze and reduces uneaten food sitting in the water. Reduce frequency as water cools in autumn, and stop or feed very rarely once temperatures drop for winter.
It's easy to overfeed koi, since they'll often keep coming to the surface for more regardless of whether they actually need it. Watching body condition over the season is a better guide than feeding on a fixed schedule regardless of temperature.
Choosing a food for your pond
Pellet size should suit the size of your koi, smaller pellets for younger or smaller fish, larger ones for established adults, since a fish struggling to manage an oversized pellet wastes energy and can leave more debris in the water.
A basic wheatgerm food for the cooler shoulder seasons and a proper summer growth or colour food for the warmer months covers most koi keepers' needs without needing a large range of different products through the year.
What we stock
Everything below is in stock with us, priced with delivery worked out, and packed and posted by hand in the UK.
Tetra Goldfish Flakes
Complete goldfish flakes in several pack sizes, with a shared formula across the family
From£3.02
Tetra Goldfish Granules
Complete granules for goldfish, with a shared formula across both pack options
From£3.98
Tetra Prima Mini Granules
Slow-sinking granules for mid-water and bottom-feeding fish, blending herbivore and omnivore diets
£6.10
Tetra Aquasafe
A water conditioner that neutralises chlorine and heavy metals, with an added vitamin B mix
From£6.41
Tetra Pond Fish Food Variety Sticks
Complete Tetra Pond Variety Sticks in three colours, across four pack sizes
From£6.41
Tetra Koi Pond Fish Food Sticks
Complete fast-soaking Tetra Pond Koi Sticks, available in four pack sizes
From£6.41
Tetramin
Complete TetraMin flake food for ornamental fish, offered across several pack sizes
From£2.39
Tetra Temperate Flakes
Complete flakes for subtropical fish kept at 18–23°C, with vegetable ingredients
£6.99
Tetra Pond Fish Food Sticks
Complete fast-soaking Tetra Pond Sticks for pond fish, in seven pack sizes
From£4.77
Tetra Japan
Sinking dry pellets for fancy goldfish, with pack-specific label information shown clearly
From£4.56
Common questions
- What should I feed koi in winter?
- Very little or nothing at all once water temperature drops low enough, since a koi's digestion slows down dramatically in cold water and undigested food can sit in the gut. Most koi keepers stop feeding over the coldest months and resume gradually as the water warms in spring.
- Can I feed koi normal fish food?
- It's better to use food specifically formulated for koi, since they grow much larger than typical pond fish and have different seasonal digestive needs, particularly around temperature. A general pond fish food isn't necessarily wrong, but a koi-specific food better matches what they actually need across the year.
- How often should koi be fed in summer?
- Several small feeds through the day, each eaten within a few minutes, works better than one large feed, since it mimics natural grazing and reduces uneaten food affecting water quality. Adjust the amount based on how quickly it's eaten rather than a fixed portion.
- Does colour-enhancing koi food actually work?
- Colour-enhancing foods contain natural pigments intended to bring out reds and oranges in a koi's markings, and many keepers do see a visible improvement over time, though the effect varies between individual fish and isn't guaranteed for every koi.
Related
Written by Matt Garnett, who runs Giddy Pets and is a lifelong pet owner — not a vet. This is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your animal. How we write these guides.