Good koi food is a staple pellet in the right size, fed in an amount that matches your water temperature, and stopped entirely once the pond drops below 50°F. That covers about 90% of what most pond owners need. The other 10% is choosing between growth, colour and wheat-germ formulas and knowing when each earns its price. This guide covers both, with the temperature chart we work from at the shop.
Short answer: Feed a 32% to 35% protein staple through most of the season, switch to a wheat-germ or all-season formula below about 60°F, and stop feeding below 50°F. Feed what the fish clear in five minutes, two to four times a day in summer, once a day or less in the shoulder seasons. Match pellet diameter to fish length: roughly 3.5 mm for an 8-inch koi, 5 mm at 12 inches, 7 to 9 mm past 14 inches. Colour food works, and fed heavily it can also yellow the whites.
What the words on a koi food bag actually mean
Bag terminology is not regulated the way pet food labelling is, so the words below describe intent rather than a standard. The guaranteed analysis panel on the back is the part to trust.
Staple
The everyday diet. Moderate protein, low fat, stabilised vitamin C for immune function, and a formulation you can feed for months without causing problems. Most staples land between 32% and 36% crude protein. If you buy one bag of koi food a year, buy this one. Browse the full koi food range to compare.
Wheat germ
A cool-water formula, not a magic ingredient. Wheat germ brings vitamin E and useful fatty acids, but the reason it works below about 60°F is that these foods are lower in protein and higher in roughage, so the remainder passes through the gut faster. Protein is only usable for growth above roughly 59°F; feed a high-protein pellet in cold water and most of it passes straight through the fish and lands in your filter as ammonia. See the wheat germ koi food we stock.
Growth
High protein, and usually high fat as well. Saki-Hikari Growth is 40% protein and 9% fat minimum; Nijikawa Growth is 45% and 10%. These are warm-water foods for water consistently above about 68°F, and they only make sense if your filtration and aeration can absorb the extra waste. No food produces "fat-free growth". Overfeed a high-protein diet and you get a fat koi.
Colour enhancing
Koi cannot manufacture red or yellow pigment. They have to eat it, in the form of carotenoids: astaxanthin from krill and Haematococcus, and zeaxanthin from spirulina. Colour food is simply a staple with more of those included. It genuinely works, and the honest caveat is below.
All-season and multi-season
A middle-protein blend with wheat germ included, fed across a wide temperature band so you are not switching bags every six weeks. Saki-Hikari Multi Season is the best-known example at 37% protein and 5% fat, with wheat germ, spirulina and Hikari-Germ probiotic. Useful in a climate like ours, where a San Jose pond can swing 15°F between February and April.
Probiotics
Hikari's Hikari-Germ is a live microorganism added to the Saki-Hikari line, and several other brands add digestive enzymes or their own cultures. The claim is better nutrient uptake and drier waste that breaks down faster, meaning less load on the filter. Whether that justifies the price gap depends on how hard you are pushing the pond.
Floating or sinking
Feed floating pellets as the default. Not because koi prefer them, but because floating food lets you count heads, spot the fish that is not eating three days before it looks sick, and net out what was left. Sinking pellets suit very large fish that struggle at the surface and shy koi in a new pond. What they cost you is visibility.
How to choose koi food by what you actually want
Growing a young fish as fast as it will safely go: Saki-Hikari Growth or Nijikawa Growth, fed above 68°F, three or four small meals a day rather than one large one. Split feeding matters more than the brand. A koi has no true stomach: food moves through a straight gut several times its own body length and is absorbed continuously, so small frequent meals are used far better than one big one.
Deepening reds before a show or after a dull winter: Saki-Hikari Color Enhancing (40% protein, 6% fat, astaxanthin plus spirulina, for water above 64°F), or Aqua Master Color Enhancer at 40% protein if you want the same idea at a third of the price. Compare the colour-enhancing options side by side.
One bag, all year, minimum fuss: Saki-Hikari Multi Season, or Sea Side Aquatics All-Season if the budget is tighter.
Spring and autumn, or a pond that runs cold: Hikari Wheat-Germ at 32% protein, or Aqua Master Wheat Germ at 36%. The Aqua Master version contains no spirulina and uses beta-carotene instead, which is a reasonable choice if you are protecting the whites on a Kohaku.
A mixed pond of pet-quality fish and a budget: Aqua Master Staple at 32% protein starts at $13 a bag. Here is the part nobody selling koi food likes to say: for a garden pond of a dozen mixed koi that will never be entered anywhere, a $13 staple fed correctly beats a $90 premium food fed carelessly. Premium food earns its money when you are growing a specific fish toward a specific result. Spend the difference on aeration instead.
The koi feeding chart: how much and how often by water temperature
Buy a pond thermometer and put it at mid-depth, not at the surface. Everything below keys off that reading, not the air temperature or the calendar. Percentages are of total fish body weight per day, split across the day's feeds.
| Water temp (°F) | What to feed | Feeds per day | Daily amount (% of body weight) |
|---|---|---|---|
| Below 50 | Nothing | 0 | 0 |
| 50 to 55 | Wheat germ | Every other day, sparingly | 0.25 to 0.5 |
| 55 to 60 | Wheat germ or all-season | 1 | 0.5 to 1 |
| 60 to 65 | All-season or staple | 1 to 2 | 1 to 1.5 |
| 65 to 70 | Staple; colour food from 64 up | 2 to 3 | 1.5 to 2.5 |
| 70 to 80 | Growth, staple or colour | 3 to 4 | 2 to 4 |
| 80 to 86 | Staple, and back off | 2 | 1 to 2 |
| Above 86 | Staple or nothing; run aeration hard | 0 to 1 | 0 to 1 |
Three things this table is telling you that the bag will not.
The top end matters as much as the bottom. Above 86°F, dissolved oxygen falls, koi metabolism is already stressed, and feeding adds a biological oxygen demand exactly when there is none to spare. Some labels quote an upper limit of 93°F. We do not feed anywhere near that.
Spring is the dangerous part of the year, not winter. Aeromonas, the bacterium behind most ulcers, becomes active around 48°F, while your koi's immune system is only around half strength at 65°F. That gap, roughly 50°F to 65°F, is when ulcers appear. Feed lightly and digestibly through it, and resist the urge to start growth food the first warm week in March.
Stop at 50°F and restart above 55°F. Below 50°F digestion effectively stops, and food sitting in the gut of a dormant koi is a genuine risk. On the way back up, wait until the pond has held above 55°F for several consecutive days rather than reacting to one sunny afternoon.
From the shop: Every spring we get calls about koi with ulcers in San Jose ponds that overwintered without a scratch. It is almost always the same story: the pond hit 56°F in the afternoon, the fish came up begging, and they got a full summer ration of high-protein food. Feed the thermometer, not the fish.
Pellet size by fish length
Pellet diameter is the specification most often ignored and the easiest to get right. Too big and it gets spat out and fouls the water; too small and a 20-inch koi burns more energy feeding than it gains.
| Koi length (inches) | Koi length (cm) | Pellet diameter (mm) | Typical bag label |
|---|---|---|---|
| Under 4 | Under 10 | 1.7 to 2.8 | Baby |
| 4 to 8 | 10 to 20 | 3.5 to 4.0 | Small |
| 8 to 14 | 20 to 35 | 4.8 to 5.5 | Medium |
| 14 and up | 35 and up | 7.5 to 9.0 | Large |
In a mixed pond, size down rather than up. Big koi eat small pellets happily; small koi cannot eat large ones at all, and with a couple of 24-inch Chagoi in the pond the small fish lose out. If your fish span 6 to 20 inches, feed a medium pellet and add a handful of small alongside it.
How much is too much, and what overfeeding does to your filter
The five-minute rule is a reasonable starting point: feed only what the fish clear within five minutes, then net out anything left. It has two failure modes.
First, it measures appetite, not requirement. A pond with two Chagoi in it will pass the five-minute test at three times the food the pond can biologically process, because Chagoi keep eating long after they need to. Second, appetite climbs faster in spring than your biofilter's bacterial population does, so a warm week in May can produce measurable ammonia in a pond that read zero in April.
Everything a koi does not absorb becomes ammonia. Your biofilter converts ammonia to nitrite and nitrite to nitrate, which means the filter produces nitrate rather than removing it. Nitrate leaves through water changes, plants or a bog, and nothing else. The chain is: more food, more ammonia, more nitrate, more algae, more water changes. Keep a water test kit on the shelf and test whenever you increase feeding. If ammonia reads above zero, cut the food by half before you reach for a treatment bottle.
Honest talk about colour food and shiroji
Carotenoid-heavy diets can yellow the white ground on a Kohaku, Sanke or Showa. This is not a rumour spread by rival brands. Carotenoids are fat-soluble and accumulate in the fish's tissue, so heavy or year-round feeding of concentrated colour formulas is a well-documented way to tint the shiroji and produce muddy, over-pigmented reds. Hikari's own guidance warns against too much spirulina for the same reason.
What we suggest: feed colour food as part of the diet rather than the whole of it. A 50/50 rotation with a growth or staple pellet through the warm months gives most of the benefit with much less risk. Fish with a lot of white get less; fish with heavy hi and no white to spoil, such as Benigoi or Hi Utsuri, can take more. White quality is also driven at least as much by water quality and stocking density as by anything in the bag.
What not to feed, and which treats are fine
Keep treats under about 20% of what goes in the pond. Pellets are formulated to be complete, and anything else dilutes that.
Avoid entirely. Bread and refined flour products: close to no usable nutrition and a recognised cause of digestive trouble. Dog and cat food: built around animal fats and dairy proteins that koi digest poorly, and a long-term route to fatty liver. Dried peas and raw sweetcorn: starchy enough to cause blockages. Anything oily, salted or seasoned from your kitchen.
Fine in moderation. Orange and watermelon segments, romaine lettuce, shelled peas cooked soft, cucumber slices, and duckweed straight off the pond surface. For protein, krill, mealworms and bloodworms are excellent and close to what koi eat in the wild. Feed treats in warm water only. Our koi feeding reference page covers hand-feeding and taming in more detail.
The koi foods we stock, side by side
Protein and fat figures below are manufacturers' guaranteed-analysis minimums. Where a figure is not published, we left it out rather than estimate.
| Food | Crude protein (% min) | Crude fat (% min) | Best used at (°F) | Buy it for |
|---|---|---|---|---|
| Saki-Hikari Growth | 40 | 9 | Above 68 | Maximum size gain on young fish |
| Saki-Hikari Multi Season | 37 | 5 | 55 to 86 | One bag for most of the year |
| Saki-Hikari Color Enhancing | 40 | 6 | Above 64 | Deep hi on show fish |
| Hikari Staple | 34 | 3 | 60 to 86 | Straightforward daily feeding |
| Hikari Wheat-Germ | 32 | 4 | 50 to 64 | Spring and autumn |
| Hikari Gold | 35 | 3 | 60 to 86 | Daily food with mild colour support |
| Aqua Master Staple | 32 | 3 | 50 to 86 | Best value everyday pellet |
| Aqua Master Growth | 38 | 3 | 70 to 86 | Summer growth on a budget |
| Aqua Master Color Enhancer | 40 | 3 | 65 to 86 | Colour with spirulina, low cost |
| Aqua Master Wheat Germ | 36 | 3 | 50 to 70 | Cool water, no spirulina |
| Sea Side Aquatics All-Season | 32 | 3 | 55 to 86 | Large ponds, bulk feeding |
| Sea Side Aquatics Quick Grow | 32 | 3 | 60 to 86 | Steady growth, easy on water |
| Nijikawa Growth | 45 | 10 | Above 68 | Serious growth programmes |
| Nijikawa Professional (sinking) | 43 | 12 | Above 68 | Jumbo fish that feed deep |
| Nijikawa Four Seasons | 35 | 8 | 55 to 86 | All-round feeding, 5 mm only |
Two notes. The temperature columns are our working recommendations, drawn from label guidance but capped at 86°F and floored at 50°F; several labels quote wider ranges than we would use. And Nijikawa Color Genesis is a food we stock and rate, but its guaranteed analysis is not published, so it is not listed. For what else belongs in the shed alongside the food bin, see our koi food and pond supplies hub.
Storing koi food so it is still worth feeding
Koi food degrades faster than most people assume, and the first thing to go is the vitamin C, which is exactly what you are relying on for immune function. Even stabilised vitamin C is close to spent after about six months. Buy the bag size you will finish inside that window, not the one with the best price per pound.
Store it cool, dark and dry, in a sealed container at a roughly constant temperature. A garage shelf that hits 110°F in August is a bad place for a $300 bag. Do not refrigerate or freeze it: each time you take the container out to scoop, the contents warm, condensation forms inside, and damp pellets grow mould. If a bag smells sharp or the pellets have gone soft, throw it out. Buying in bulk is genuinely cheaper per pound and right for a heavily stocked pond in summer. It is the wrong call for a 1,000-gallon pond in October.
If you only change one thing
Get a thermometer to mid-depth and feed to the number on it. More koi are damaged by food fed at the wrong temperature than by cheap food fed at the right one. Then run a staple pellet as the backbone of the diet, add wheat germ for the shoulder seasons, and treat growth and colour formulas as tools for a specific job rather than defaults.
Frequently asked questions
What is the best koi food?
For most ponds, a 32% to 35% protein staple in the correct pellet size, fed to water temperature. Saki-Hikari Multi Season is the strongest all-round premium choice; Aqua Master Staple is the best value. "Best" depends on your goal: growth formulas above 68°F for size, wheat germ below 60°F for digestibility, colour food in warm water for hi.
How often should I feed koi?
Two to four times a day between 70°F and 80°F, once or twice between 60°F and 70°F, once a day or less below 60°F, and not at all below 50°F. Several small feeds beat one large one, because koi have no true stomach and absorb food continuously as it passes through the gut.
Can you overfeed koi?
Yes, and it is the most common mistake in the hobby. Excess food becomes ammonia, which the biofilter converts to nitrite and then nitrate. Nitrate accumulates until you do a water change. Symptoms show up as cloudy water, string algae, and ammonia readings above zero after a warm spell. Halve the ration and test the water.
Does colour-enhancing koi food turn the white areas yellow?
It can. Carotenoids such as astaxanthin and the zeaxanthin in spirulina are fat-soluble and accumulate in the tissue, so heavy or year-round colour feeding risks tinting the shiroji and muddying the reds. Rotate colour food with a staple or growth pellet rather than feeding it exclusively, and feed less of it to fish with a lot of white.
When should I stop feeding koi in winter?
Stop when the pond has settled below 50°F. Digestion effectively halts there, and undigested food in a dormant fish is a real risk. Restart only when the water has held above 55°F for several consecutive days, and start with a wheat-germ formula in small amounts rather than the food you were using in August.
Can koi eat bread or dog food?
No to both. Bread offers almost no usable nutrition to a koi and is a known cause of digestive problems. Dog and cat foods are built around animal fats and dairy proteins that koi digest poorly, and regular feeding leads to fatty liver and poor development. Use orange, watermelon, lettuce or krill as treats instead, keeping treats under about 20% of the diet.