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Feeding Koi in a Proper Koi Pond With No Natural Forage

Feeding Koi in a Proper Koi Pond

“Can you see the hair in my nose when I tilt my head this far back and look down my nose at you?” -A Bitter Old Man Who Knows Everything About Koi, Except Facts.

“Proper” Koi ponds are engineered to be easy to clean, and they meet the housing needs of the fish over any other ancillary purpose. What defines a “proper” koi pond is dependent upon the ego of the

Grouchy old men whose children have no use for them can make themselves feel important by belittling others on message boards
Grouchy old men whose children have no use for them can make themselves feel important by belittling others on message boards

person you’re talking to. The more inflated the ego, the more narrowly you will find “proper” is defined. You might also notice that “proper” among the most bellicose of pundits is ONLY equivalent to what THEY have installed in their yard, to the exclusion of all other obviously “wrong” concepts.

I digress, but thanks for allowing me. A proper Koi pond by any definition is a rather sterile above ground or attractive in-ground container of water lined with rubber. The filtration system is usually copious, but so effective as to render water that is “gin” clear. This is one of the two main ponds I have, and in truth I enjoy it for my finest collector-Koi because it’s “All about them” and they really thrive with that kind of environmental control. As a high performance machine, the filtration requires regular adjustment, backwashing and tweaking and the water requires regular testing because there is no stone to buffer pH. The fish show up beautifully on the black rubber background and cleaning the stuff off the bottom is as easy as pushing it to the bottom drain with a hose with fish in place. There is no Spring cleanout. Instead, my investments in time are small, but almost daily. In my case, the “proper” Koi pond is a fairly obtuse, ugly box of water otherwise. I mention this in a nutrition article because “Where is the natural forage?” There is very little I must supply ALL the nutrition to these fish and so I have complicated, but gained greater control over, my hobby.

Indoor Koi Ponds

Indoor Koi ponds are worth mentioning because there is absolutely ZERO natural forage and they face challenges of maintaining coloration without the benefit of unfiltered sunlight. These installations and feeding situations are difficult. Food selections must be optimal, some fresh proteins and plant material should be provided, and as much natural sunlight as possible brought to bear on the fish.

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Over Feeding Koi and Pond Fish: The Most Common Beginner Mistake

Over Feeding Koi and Pond Fish: The Most Common Beginner Mistake

Overfeeding koi and pond fish is very common beginner mistake.
Overfeeding koi and pond fish is very common beginner mistake.

The majority of hobbyists, if they were to make a feeding mistake, would overfeed. This is because the feeding process is arguably the best time you have with your fish. At feeding time, Koi come up to eat so you can see them, and anyone with a maternal instinct will thrill to watch their favorite fish engulf food with such Koi-ish zeal. Overfeeding is engaged anytime the fish are eating more than they need. So, for a fish farmer with a mud pond full of small fish he’s trying to grow, he would feed about five to seven times per day. That would not be overfeeding. But in a typical ornamental pond with a reasonable collection of fish, that feeding rate would be excessive and the wastes therefrom would strain the limits of what can be biological reduced. Means: You water quality will decline.

Fish that are overfed in typical ornamental pond facilities will eventually develop ponderous bellies and begin to look a little bit like tadpoles, with the big body and the wispy tail. That is not a terminal event for the fish but the impact on the liver and other internal organs can and will be severe. Farmed fish that have much more room in lakes or large ponds can be fed considerably and they will not develop as much obesity as reguar backyard pond fish.

Fish should be fed no more than three times per day. In cooler water they should only be fed once per day, if that. In much warmer water, three times per day is not ‘crazy’ however, you have to be wary of bacterial blooms (cloudy water and low oxygen levels) if you feed heavy and there’s a lot of waste.

Fish should be fed for about five minutes per feeding. If they don’t come up and eat voraciously, they are telling you that they are too cold, or too warm, feed light. If they come up and “hit hard” you can sprinkle food on the water for five minutes as long as there are fish there to carry it off. Pretend it’s a game, NEVER LET IT FLOAT. So, feed the fish as they approach and let them carry it all away, leaving none to float into the skimmer or filter.

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Do You Even HAVE To Feed Your Koi and Pond Fish?

Do You Feel The Need To Feed?

-Not every pond has to be fed. I know it sounds amazing but it’s true. And there’s a converse too. I’ve heard Aquascape installers say that their ponds never need to be fed and that’s equally wrong. If you’ve stocked with koi, chances are you will need to feed something. If you stock heavily with Goldfish, you will probably need to feed.

But if you have Mud bottom ponds with freshwater feeds and a ‘bug light’, you have arguably “handled” the fishes’ feeding requirements. This is because in spring fed mud ponds, there’s always something to eat. Either a variety of amphibians in the Spring and sides of the pond, or copepods and worms on the mud floor of the pond. If you suspend a plain light bulb fixture over most ponds and run it at night – insects will be attracted to the light and fall into the Koi’s waiting mouths. This advice does not hold true for stocking farmers who have many mouths to feed in such ponds. I hope this brings home the concept of natural forage. Does your pond have natural forage?

No matter, if the bellies are filled in and not getting thin, adjust the additional food accordingly. In a big outdoor eco system pond you might not have to feed the fish at all.


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Koi Treats: Feeding Silkworms And Grapefruit And More

Someone said that it would be helpful to write an article on Koi treats. And so I am. But in this article I am only going to comment on what I personally have given my fish. There’s a lot out there, how much of it has actually been tried and how much is theory I shudder to think.

Silk worm pupae


Available various places in sealed silver bags, this delicacy drives Koi crazy. Really, really nutty. They love them. I guess when a silkworm gets old and stops making silk, it’s “history” and is freeze-dried for Koi. Lip-smacking good, I guess. Fed in abundance, the protein can accumulate a good bit of nitrogen (ammonia) in the water so please check Ammonias if you’re going crazy with Silkworm pupae. I never had trouble in warm water but I did feeding SWP in cold water. A little bit every day or two is enough.


Cut the grapefruit on it’s equator (widest latitude) and then again cut those halves into halves. So you have quarters. They float. The fish will be attracted at once. Watch out the skins don’t jam up a pump or clog your skimmer. Fed too much, the vitamin C acid will scorch the lips of your fish to a pale pink color, no harm – just back off. Once per week is plenty.


They liked it but not as much as Grapefruit. It doesn’t supply much nutrition so I have not done this as much as grapefruit.

Orange slices

Vitamin C - ascorbic acid in koi and pond fish food is one of the most important vitamins.
Vitamin C – ascorbic acid in koi and pond fish food is one of the most important vitamins.

Big fish will earnestly take Mandarin orange slices right out of your hand. Very cool, delicious to the fish, I guess, and loaded in Vitamin C. Larger seedless oranges can be cut as Grapefruit [above] and will do as well.


The pain in the neck to me about these was that they sank fast. And if the Koi didn’t see them go in, they miss them on the bottom. So there’s the chance of wasting the peas and polluting the pond. So be careful to let the fish know you’re there, and “here come the peas” and all that. They say that the peas could be skinned. Yeah, sure, I have time for that, how about you? My Koi liked the peas quite a bit, when they realized they were there. I had a Tancho Goshiki that especially liked the peas which showed me that not all fish are alike, personality-wise.


Nutritionally invisible, but perhaps the least messy of “greens” for the fish to munch on if you like them to have something to eat like that. Don’t bother with Iceberg lettuce. Get the darkest Romaine you can and cut it into six-inch strips of the thinness suitable for your fish. They will chomp on the thick centerspines of the leaf later.


Delicious to koi. Cut off the roots because they are a mess!!!! I repeat, cut off the roots. Then fracture the plant so it’s barely hanging together and toss it on the pond upside down, foliage in the water. The larger Koi especially will eat the youngest leaves first and then pretty much annihilate the whole plant. Do NOT offer roots because the Koi will rip them up and send them directly to your pump’s impeller which will summarily choke to death.


Koi will eat ALL of this. If they can. They love it, so do Goldfish. In REALLY large ponds a balance may be struck where the Koi cannot or will not eat all of it but in a regular 11 x 14 pond Duckweed will be a shortlived commodity. It’s easily grown outside their abode in vats, babypools and tubs in a sunny spot with six inches water, fairly well circulated, with a small dead fish, or a handful of Koi food, for fuel.


Koi eat earthworms, Georgia reds, nightcrawlers, pinks, etc. Some people say that you should drown the worms in water first because the “hazardous soil” is expelled from the worm when it drowns and goes flaccid. Uh, my fish wouldn’t eat them dead like that, either. So go figure. Fresh, active earthworms are well accepted and safe after the fish take the necessary half hour to figure them out as food. When the first Koi hits a worm, the rest quickly catch on. It’s not taken as immediately as Grapefruit, which is strange. Isn’t it?


sardines can be taken by koi as a treat
sardines can be taken by koi as a treat


Koi can be trained to like fish. A very good friend of mine, named Tom, feeds his Koi thawed Sardines chopped up. Nutritious? YES! And sardines (being from salt water) are less likely to carry parasites applicable to Koi. So, again, in moderation, these treats are okay for Koi. And certainly well enjoyed.


We discussed Cheerios in the winter-feeding section but let me restate that ANY time of year, Koi will appreciate Honey Nut Cheerios as a treat. It is low residue and low nitrogen, what’s not to love? A+


Yes I did this. It wasn’t a smashing success and they left it alone for a little while but I took some fried chicken to the Koi. I ate the fried part (duh) and gave them the white meat, in pinches. They looked at it and swam around it a while and then hit it with pretty good gusto. But it made some debris when they chewed it with their back teeth and wasn’t “loved” so I include it here as something they’ll take, but not necessarily love.

Is there anything I probably should NOT feed Koi as a treat?

I’ve heard that grapes can contain some oxalates and that apple seeds contain cyanide. The math on these says that if you got a Koi to eat a cubic meter of grapes or appleseeds in a day’s time, said Koi could perish from the crystallization of the oxalates in his kidney. For your information, a Koi that could eat a cubic meter of grapes in a day would measure about forty-two feet long and weigh in at 2,300 pounds. So I would say this:

Dr Johnson’s Notes On Koi Treats:

“If you would eat it, and the fish can eat it without it dissolving in, or polluting the pond, try it, and see if they like it. Don’t feed any treat so much as to replace their interest in nutritionally complete staple food.”

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What Size Pellet to Feed Koi and Pond Fish?

It’s nice to feed a mixed size pellet feed. They make them, you know.

Small fish need small pellets that they can wholly engulf, but they will spend time chasing the biggest pellets. It would be better for the fish if they were given a small pellet they could entirely engulf. They could fill their stomachs instead of scraping off a meal over a lengthy time.

Can small fish eat large pellet? Yes, but that is only by badgering the large pellet around the surface of the pond as it softens in the water, and eating off it like a giant peach.

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Koi and Pond Fish Cannibalism – Koi and Meat

Koi Cannibalism

Well, what discussion of Koi Nutrition would be complete unless we talked about the Koi’s more jocular habits of eating fry, frogs and each other? More fantastic than fact, here are some things you might not know.

Large Koi and large frogs

If a tree frog falls in with big Koi it might be made into a meal
If a tree frog falls in with big Koi it might be made into a meal

In the Springtime, there’s these little frogs called Spring peepers. You can here them in low areas of your yard or the woods, living in puddles. In the cold months of Spring they spawn and lay strands of eggs. And sometimes, they get in your pond, and a big Koi catches one. Or, like at my house, all the Koi catch one. And so you get up in the morning and all your Koi have a pair of frog legs sticking out of their mouths and they like the taste pretty good, but they can’t work it down. So they swim around with the frogs in their mouths like pacifiers. Some of the largest fish can get the frogs down, some eventually spit them out and you have to net them out or they will decay and make a mess.

Koi in tanks with Oscars

I saw two different situations of similar type. A large fish tank with the unlikely tank mates of Oscar Cichlids *and* Koi. The Koi were initially brought home as live food for the Oscars instead of Goldfish or guppies. However, the Koi eluded the Oscars and, as Americans always pull for the underdog, the Koi were allowed to remain in the tank with the Oscars. But the gentlemen keeping the Oscars were only actually “keeping” the Oscars (Good luck, Koi!) so the food being put in the tank was suited for the Oscars: either worms or little fish. To survive, the Koi became very effective and ferocious guppy and goldfish eaters. Habituate or starve. I’ve always said that.

Koi fry and the Cannibals

Finally, you should know this about baby Koi. A momma Koi will lay many tens of thousands of eggs per spawn. And her babies will be very numerous. And these fry mature at differing rates. The brown solid-colored babies will mature faster than the bright solid-colored fish and these babies will mature more quickly than any two or three colored fish. So it happens that often you see several much-larger baby fish in a spawn swimming about with a tiny sibling tail in its mouth. These cannibals eat prodigiously and the more they eat the bigger they get and the faster they get there. So breeders know to remove these cannibals. If you don’t you will have a nice collection of Ogons and no multicolored fish in a spawn. So Koi can be cannibalistic when they’re fry. Later in life, it would be exceedingly rare to see a large Koi eat a small one.

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Feeding Koi in an Aquascape Pond

Feeding Koi in an Aquascape Pond

Big ecosystem ponds are full of natural forage. You can feed them less if you feed at all. Just notice that the bellies of the fish stay filled out.
Big ecosystem ponds are full of natural forage.

Very sizeable Aquascape ponds

-I have a friend named Greg Wittstock who has an Aquascape pond of probably an acre and a half. Maybe larger. And in this pond there is a teeming ecosystem of turtles, fish, plants, insects, and amphibians. If a fish were to die of starvation in his pond, we would have to assess the fish as being brain damaged. There’s plenty to eat.

Many of the large Aquascape installations will have a goodly amount of live food and plant material for the fish to be sustained on. This is great from the standpoint that you can feed conservatively, and if you are ever away or forget to feed the fish chances are they’ll find something juicy in the gravel or they could prune your plants.

Foraging in the gravel is an important way that fish prevent that very gravel from stagnating. (Or you can toss a pair of boisterous kids in for a weekly summer swim like Ellen B. in Batavia does.)

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How to Store Koi and Pond Fish Foods

Proper Food Storage

Store koi and pond fish food in tupperware and in the refrigerator.
Store koi and pond fish food in tupperware and in the refrigerator.

-Sometimes you luck out and get a deal on bulk foods. Or, a manufacturer offers larger containers than your fish can eat in a season. Too bad. I do NOT recommend that you buy big bags of food unless your fish can eat it all in a season. This is because it’s necessarily difficult to keep 45 pounds of food in the fridge. Of course, if you CAN, do it! Otherwise, the fish food sits in the bag in a “cool dark place” and weevils hatch in it and the food is lost. Or moulds grow in it, on the condensation-side of the bag and it’s lost. Or, the cats tear out the bottom corner of the bag and the food spreads across the floor of the garage like a cancer. Can you tell “I’ve been there, done that”??

Refrigerate foods, DON’T freeze them. Freezing damages (lyophilizes = freezer burns) the fats in the food and so the fat-soluble vitamins are compromised.

Foods which are packed in nitrogen (no oxygen) by the manufacturer are better than food which is in cans with oxygen. If you can find food which has a bag that allows expression of air from the bag and resealing, that is optimal.

Old Food?

If food begins to smell “funny” or develops a fuzz on it, changes color, sticks together or crumbles down, it’s old or “bad” and should be discarded. Feeding “bad” food will land you in a world of hurt with your fish, because much of what grows in fish foods produces what are known as “Aflatoxins” which can cause injury, deficiency, and broken backs, in fish fed these spoiled foods. Truly, fish should go hungry while waiting for you to get fresh food, rather than being fed spoiled food “just for a few days” because it matters.