In This Chapter
- Balancing the diet
- The ABCs of commercial foods
- Adding a taste of fresh foods
- Just say No to the bad foods
- Knowing when to supplement
- Adjusting food for the seasons
- Ringing the dinner bell: Feeding schedules and amounts
Just like people, koi like to
eat. And very much like people, they cheerfully consume diets high in fat or
crammed with carbohydrates without a real concern for how they pan out in the
long run (or long swim, as the case may be). Some foods that koi love to eat, like
white bread and cooked rice, provide carbohydrates but not full nutrition, and
the koi tend to load on weight with no real nutritional benefit.
The good news is that you can
provide a healthful diet through commercial foods, and you don’t have to pick
up a single earthworm or cook up a batch of greens unless you want to. In this chapter,
we tell you what koi need to eat, how to find commercial fish foods to fill
those dietary requirements, and how you can supplement those commercial foods
with foods from your garden or grocery store. We even tell you how to make your
own koi food cakes (if you feel like cooking!).
Eating Right: It’s All about Variety
No single food item provides
total nutrition for koi, which is why a variety of food items is so important.
Whether the food items are fresh (fresh from the ground, fresh from the sea,
fresh from the field) or part of a dried or frozen commercial mix doesn’t seem
to matter. The important factor is the mix of ingredients.
Ideally, a wide variety of plant-
and animal-based foods should be provided. The specifics of the koi’s natural
diet are not completely known and vary from location to location throughout
their enormous range. Commercial diets also vary in their ingredients, including
such diverse items as fish meal (made from 4–5 species), shrimp meal, krill,
dried insects, corn, wheat, soybeans, rose hips, spirulina, oats, rice, and
alfalfa. By combining these foods with various vitamins and minerals, several
formulas have been devised that provide all the nutrients needed by captive
koi. You can, of course, furnish a wholly fresh diet to your koi (and have no
life other than koi-feeding), or, like serious koi-keepers, you can take advantage
of high-quality commercial koi diets.
Making the Best Commercial Food Choices
Koi-food companies have spent
years and hundreds of thousands of dollars to develop diets that appeal to koi
and still offer complete nutrition in a packaged, dry form. But how can you
tell whether the food you’re buying is really a complete diet? Do federal
standards exist like the ones for baby food?
Like cuts of meat, generally
speaking, you get what you pay for with koi food. So, the not-so-good
commercial brands exist alongside the good commercial brands and the very good
commercial feeds. How can you tell which is which? Stick with us, dear reader; we
walk you through it in this section.
Warning!
Koi-food manufacturers spend a lot of money on package design because they want to catch your eye. If the label’s attractive, it helps entice you, the consumer, into picking the container up — and that’s half the battle. An attractive package can also entice you to spend more than you planned and distract you from your real goal, which is to buy good nutrition for your koi.
What to look for in koi food
Remember
When you’re purchasing koi food, size matters. Look for pellets that are keyed to the size of your koi. Young koi (4 inches or less) need a pellet small enough to eat right away, so they don’t have to wait for it to fall apart. Look for pellets about one-eighth inch across for small koi. Quarter-inch pellets are fine for adult koi.
When you’re sure you’re looking
at the right size of food, you still have some choices to make, and it’s easy
to get confused.
Basically, you want to pay
attention to the variety of ingredients and to the levels of vitamins,
minerals, protein, and fat. To narrow down your choices, read the contents list
on the container to ensure that these important nutrients are at appropriate
levels (as described later in this chapter), and that the food draws its
ingredients from varying sources.
Some details to note about koi
food products:
- The list can include vitamins and items as common as ground corn and as arcane as rose hips. Specifics as to the actual value of each may be lacking, but experience has shown that such foods are good for koi and readily accepted by them.
- Some ingredients can meet more than one nutritional guideline. (For instance, wheat germ can provide vitamins, protein, and carbohydrates, and oils can provide energy and vitamins.) Koi nutrition is not an exact science, so don’t worry about ingredients that seem to overlap. Reputable companies use formulas that have, over time, been shown to provide koi with fairly complete nutrition.
Koi are pretty simple creatures,
so you don’t need to buy 18 kinds of koi food and still wonder about the
nutritional value. You just need to stick with diets that meet the guidelines
set out here and add a few of the extra items that we will discuss in the
following pages. The following sections lay out the essentials for your koi’s
diet.
Protein
Protein is one of the most
important contents because fish need it for energy, growth, and tissue repair.
Remember
The best sources of protein in a koi diet are fish meal and soybeans. Animal protein (from chicken for example) is not as digestible. Fish sources may include whitefish meal, anchovy meal, herring meal, and shrimp meal.
The protein content may be 25 to
36 percent of your koi’s diet, depending on the season and the age of your koi.
Consider the following information as a guide:
- During the summer: Protein should be 30 to 36 percent of the diet when the energy needs of your koi are higher (during the active summer months).
- During the winter: Protein should be nearer 25 percent of the diet when koi are less active and their metabolism slows (in the fall and early winter). In southern states where the weather remains warm, your fish will not enter a dormant stage, so plan to feed them a higher protein diet year-round.
- When they’re young (under 3 years of age): Protein should be 30 to 36 percent of the diet.
Tip
Look for a food that lists protein first on the ingredients label. (All manufacturers list contents from highest to lowest according to their dry-weight quantity.)
If you prefer to stay on the
middle ground and not veer into high or low protein levels, buy plant-derived
protein sources, like wheat germ pellets. These sources generally provide
enough protein (and they’re a good source of vitamin E). You can give these to
your koi throughout the year, but they are especially important during the cooler
seasons.
Carbohydrates
Carbohydrates are another energy
source. They’re also good sources of fiber and a main component of vegetables
and fruit. (See the later section on fiber for more info on fiber in the koi
diet.) If koi don’t have carbs for easy-to-obtain energy, your koi break down
protein instead, which leads to a vastly increased output of ammonia. However, you need to strike the
right balance because too many carbs can lead to chubby koi. The correct amount
is not firmly established, but 60 to 70 percent is safe. Suitable sources for carbs
are plant-based foods such as wheat, corn, soybeans, and rose hips.
Lipids
Oils and fats (or simply lipids)
are another source of energy and a good source of fat-soluble vitamins like A,
D, E, and K. Koi derive lipids from animal-based foods such as fish meal and
shrimp meal, as well as from fish oil and wheat germ oil.
An ideal koi diet consists of 3
to 10 percent fat. The high end is for fast-growing young fish, and the low end
is for adult fish. The fat content of
the diet should come from easily digested sources, suchas wheat germ, during
the colder months when the fish’s metabolisms are operating at a reduced pace.
Vitamins and minerals
Vitamins and minerals are
important components of a koi diet (as they are for any living organism).
Little is known of the exact levels required by koi, but those included in
long-established commercial foods can be trusted.
Fiber
Fiber is the vehicle that carries
the food components through the digestive system where they are then absorbed.
The longer the food’s in the gut (within limits, of course), the more time the
fish has to absorb the nutrients. This is obviously the advantage to fiber in
the diet. However, the less fiber, the less bulk in the excreted feces, which
is important when you’re raising koi in fairly high numbers because less bulk
means less strain on your filtration system. In practice, however, your best
option is not to attempt to regulate feces composition via diet. Rather, feed a
standard commercial diet and use adequate filtration for the number of koi you
have. If you feel you must reduce the volume of the feces that your fish
produce, use a lower-fiber food, such as wheat germ pellets, as the main
portion of their diet.
Good sources of fiber are ground
corn, oats, wheat germ, and similar plant-based foods. The fiber provided by
these generally makes up about 5 percent of commercial diets, which seems to be
an adequate level. Fiber content should, like other foods, be reduced in the
cooler months. Recommended winter foods such as wheat germ pellets have a fiber
content of 2 to 3 percent.
Sinking versus floating food
Koi foods are either floating or
sinking. Sinking foods do just that, making them seem like a good choice for
fish that are usually bottom feeders (fish that swim along the bottom of
a pond or stream, taking up mouthfuls of this and that and spitting out what doesn’t
taste like food). But pond koi are another matter entirely. Because
display-quality koi can cost hundred of dollars, you most likely want to see
these living jewels. So, feeding your fish floating food simply increases your
opportunity to enjoy your treasure chest. Floating food is also practical for
three reasons:
- It helps you keep track of how much food you actually drop into your pond.
- The food disperses over the surface of your pond, giving each fish a chance to feed.
- It gives you a chance to interact with your fish, to see who’s feeding and who isn’t, and to check out who may have scale or other health issues (see Chapter Spotting and Treating Common Koi Ailments for info on what to do about health and scale problems).
Because koi fry understand from
day one that food comes from the sky and stays on the pond surface, your koi
already know how to eat a floating commercial diet. Koi just out of the egg are
often brought up on flake food by the breeder and then graduate to floating
pellets.
Does this stuff ever go bad?
Don’t rely on the old sniff test to see whether
your koi food is still good. You can’t really tell whether it’s gone rancid
because they all smell pretty bad even when you open them!
Although few fish foods are dated, try to buy a
quantity you can use within four months. Also, buy from a store that has a
high turnover rate so you’re not buying food that’s been on the shelf for a
couple of months. Some brands actually have use by dates on the package,
which makes it easier to tell whether the product is fresh.
If you want to be extra-cautious (because you’re
new to koi-keeping or have some very expensive koi in your pond), you may
want to store the open container in your refrigerator to slow down
deterioration. Some koi-keepers buy a six-month supply, decant a month’s
worth into a container, put the rest in freezer bags, and store the bags in
their freezer until needed.
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In fall, when the pond waters cool,
we suggest you use sinking pellets. Koi are less active in cooler water, so the
sinking pellets are easier for the koi to feed on. Just don’t go overboard in
quantity because your fish won’t be nearly as hungry as they were in the warmer
months. (We talk about seasonal feedings and food quantities later in this
chapter.)
Remember
When you use sinking pellets, broadcast them over the surface of the pond so they’re dispersed as they sink. The quantity is the same as for floating pellets.
Adding Some Simple (And Lively) Treats
Although the commercial diets
provide good nutrition to your koi, you can offer snack foods in limited
quantities from your grocer, your garden, or your local bait store that your
koi will obviously enjoy. If you feed treats daily, reduce the amount of
commercial food. Feeding a diet composed entirely of fresh foods is not
recommended because it’s extremely difficult to provide the dietary variety necessary
for good health.
Try these as treats in spring or
summer:
- Romaine lettuce: Cut the head into quarters and toss them into the water. It may take a while, but your koi put their lips and mouths to good use as they shred and devour the lettuce.
- Oranges: Slice a whole orange into six sections, but leave the skin on. Your koi can slurp out the pulp. If you want to prolong the process, cut across the orange to create floating orange slices. You’ll see a bobbing-for-apples action, only in reverse.
- Earthworms: Toss these into the pond, one at a time, and watch what happens when your koi discover them. This is one of the best natural foods you can provide, and even if you overfeed, it doesn’t affect the water quality.
Tip
Earthworms are especially useful as a conditioning food before spawning or as an end-of-winter appetite wakeup. You can dig these from your garden — maybe — or you can buy them from bait stores. We buy ours by the 500-lot from a mail-order fishing supply company and store them in our refrigerator.
- Live crayfish: When you toss a few live crayfish into the pond, you’ll be reminded of the koi’s closeness to their wild brethren, the carp.
- Freshwater glass shrimp (also called grass shrimp): Add a half cup to your pond and watch your koi take on the treat.
Note: Other people
feed live tadpoles, but we like tadpoles too much to feed them to our koi.
Remember
Live foods are only an addition to the commercial diet. They don’t offer a nutritional diet by themselves (and they’re too expensive to be a steady diet anyway).
Avoiding Foods that Do No Good
Koi have extremely hearty
appetites, and it therefore comes as no surprise that they will consume foods
that are not necessarily good for them. The foods discussed in this section are
tempting to use because they are quite easy to come by and relished by koi. However,
they serve little purpose in the diet and should be avoided.
Most of us can remember going to
a goldfish or koi pond sometime in the not-so-distant past and maybe tossing
cubes of white bread to the gaping mouths. White bread provides very little
nutrition and lots of carbohydrates — not good for your koi.
Making your own koi cakes
Adult or subadult koi (8 inches or longer) may
benefit from a home-cooked meal, or rather, koi cubes. These will provide a
variety of fresh ingredients not usually found in commercial diets. In
addition to being a welcome change of pace for your koi, the cubes are
another way of introducing variety into the diet. The following is the recipe
for this delicacy:
1. Chop each of the following ingredients separately in a food processor or a chopper (we use a small electric chopper). 10 ounces frozen, chopped collard greens 5 ounces frozen green peas 5 ounces whitefish or imitation crab meat 1⁄2 green pepper, chopped 1 tablespoon each: freeze-dried tubifex worms (available at any pet store), wheat germ 1 teaspoon montmolinite 2. Combine all ingredients and then puree them. 3. Add the pureed ingredients from Step 2 to 21⁄2 cups of cold water. Mix well. 4. Combine the following ingredients in a separate bowl and mix well: 1 teaspoon liquid vitamins, like you’d buy in a pet store 8 packages unflavored gelatin 21⁄2 cups boiling water 5. Stir the hot mix into the cold mix. 6. Spray mini ice-cube trays or mini muffin tins with an aerosol oil spray, fill with the final collard mixture, and freeze. The frozen cubes will thaw rapidly when you put them into the pond and can be used as a replacement for the usual diet on a random basis. Feed as you would other food — as much as the fish will consume in 5 minutes or so. |
Trout pellets are another food to
avoid — some people are tempted to feed them to koi because they’re cheap and
large. These pellets are a high-protein food designed for rapid growth in trout.
You want your koi to grow at normal rates so they become well shaped as opposed
to bloated.
Supplying Supplements
Koi-food sales are big business,
and the food manufacturer who can make a convincing case for food supplements
is richer than one who can’t. Some manufacturers promote rapid growth or brighter
colors, while others push the concept of treats for special occasions, in
celebration of an event, or as a reward.
Do your koi need these
supplements? You can answer this question yourself. You know if you’re raising
fry, or if your brightly colored koi could benefit from a color supplement (see
the nearby sidebar, “Color-enhancing diets”).
Do koi need treats? Probably not.
Koi don’t need to be motivated the way humans do. On the other fin, maybe
offering treats makes you feel as if
you’re providing a better diet or a more interesting life to your fish. Or
maybe offering these food items results in more time and interaction with your
fish. If so, go ahead. But like the labels say, offer these foods in
moderation, as an occasional treat.
Color-enhancing diets
Color-enhancing diets are foods with supplements —
like carotene (the stuff that makes carrots orange and flamingo feathers
pink) or spirulina (green algae that boost red and yellow coloration). People
like to feed these enhancers because they think their fish will be brighter
and hence easier to spot in the pond.
Both of these additives enhance red coloration.
If you select a food with spirulina, remember that most koi-keepers only give
their koi spirulina supplements in September because this plant-based food is
readily digested when the water temperature drops. (Don’t feed it when the
pond temperature drops below 40 degrees F because your koi won’t feed at such
temperatures.) Just to confuse the issue, other keepers use spirulina to
brighten up their koi a month before they enter their koi in a show.
Although brighter fish colors may sound
attractive, think for a moment about your fish before you go that route.
Color enhancers add a pink blush to a koi’s white skin — not what you want,
for instance, when you’ve spent big bucks for a Shiro Bekko, a black and
white koi. On the other hand, if your prize koi are all Hi Utsuri (red and
black koi), feeding a color enhancer may turn those fish into knockouts. Use
color enhancers just once daily.
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Feeding Koi through the Seasons
One of the charms of the koi pond
is that you don’t have to feed the koi year-round. Koi stop feeding and
digesting their food when water temps near 50 degrees F. But just because it’s
50 degrees outside doesn’t mean your pond is that cool. Your filter circulates
the water in your pond twice every hour (or at least it should), so your pond
doesn’t have much of a cool sink (a calm, undisturbed area where cool
water can collect) at the bottom. As a result, your water may be warmer than
the air temperature because it can pick up heat from the sun while being moved
about by the filter’s pump.
Remember
Of course, if you heat your pond, the air temperature has less effect on the water temperature.
Use a pool thermometer to check
the temperature at the bottom of the pond in both heated and unheated situations.
Monitoring the water temperature will prevent the surprises that can arise
because of sudden weather changes or heater failure. Two types of thermometers are
- A digital version with a probe at the end of a cable for pond use
- A submersible thermometer tied to the end of a nylon cord
Make the cord long enough so the thermometer hangs near the bottom of the pond. (For obvious reasons, be sure to secure the out-of-pond end of the cord to a structure at the edge of the pond!)
You want to know the temperature
near the bottom of the pond in case you lose power some cold, wintry day. If
the bottom of your pool dips below 50 degrees, you have to take action (see
Chapter Ten
Things to Do When the Power Goes Out on what to do when your power goes out).
Following are koi-feeding
guidelines keyed to water temperature:
- Over 75 degrees: Feed floating pellets two to four times a day, as much as the fish will consume in 5 minutes or so.
- 70 to 75 degrees: Feed floating pellets two to four times a day, but add koi cubes or a treat such as earthworms or crayfish twice a week to bulk up the fish for cold resistance.
- 55 to 70 degrees: Feed wheat germ pellets twice a day.
When the water temperature falls below 59 degrees (15 degrees Celsius), koi metabolism also falls. Provide a food that’s readily digested because the friendly bacteria in the gut (that digest the food) also slow down. Because your fish aren’t active, they don’t need much protein.
- 50 to 55 degrees: Feed wheat germ pellets once a day.
- 50 degrees and below: Do not feed when water temperatures remain at 50 degrees or less.
Establishing the Timing and Right Amounts for Feedings
Koi seem to be willing to eat any
time food hits the pond surface. But when koi are fed until they’re stuffed,
their excretion rate increases, which in turn increases ammonia levels in the
water. High ammonia levels and the bloom in the bacteria that eat the unconsumed
food can overwhelm a filter that had been perfectly satisfactory. The water
becomes foul, and your fish are in trouble as they try to extract oxygen from
the icky soup they now swim in. So go easy on the feedings until you see for
yourself what quantity to offer. You can feed less at each feeding and increase
the number of feedings if you’re concerned about your koi going hungry.
Tip
Rather than measuring out a specific amount of food to feed your koi at every feeding, use the time rule: Toss some pellets into the pond and wait five minutes. If the food’s gone, toss in some more pellets and wait another five minutes. You’re looking for the amount of food that the koi eat in five minutes. The basic amount we recommend to begin with is a teaspoon of food per 5 inches of fish per feeding.
For a very basic maintenance
diet, koi need at least 2 percent of their body weight in food a day. But most
koi owners agree that capturing and weighing koi puts more stress on them than
simply tossing in food and making sure it’s gone within five minutes.
If you feed them, they will grow
One of the interesting facts about koi is that
they never stop growing. The growth rate slows as the fish reach sexual
maturity at 10 to 12 inches, but koi continue to grow throughout their lives
unless something intervenes (like the pond becomes crowded or the water
quality deteriorates). This fact explains why the 1-meter koi looms out there
like a big juicy tempting plum.
Because koi generally grow less during the winter
and more during the summer, you can actually figure out how old a koi is.
They add growth rings to their scales. Alas, if koi are in warm ponds
year-round and fed year-round, the rings are harder to count.
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Feeding times
Most koi-keepers feed their koi
in the morning, using the theory that filter can pull the waste from the pond
before the fish submerge to the bottom of the pond at night. In actuality, any
daylight hour is a good time to feed your koi, but try to stick to a schedule. You’ll
soon find your fish gathering near the feeding station just before feeding
time, getting very excited as you approach. Keep in mind that smaller amounts
of food given more frequently put less strain on your filter.
Even during the warmer months you
may have a reason not to feed your koi every day. Koi that are going to be
shipped or exhibited in a show are not fed for several days before the ship or
show date. The lack of food ensures the koi don’t excrete while in their
shipping container so they don’t have to breathe contaminated water.
Hand feeding
Many koi-keepers enjoy feeding
their koi by hand. They put the pellets in their hand, sit by the pond, and
lower their hand into the water until the pellets are floating a few inches
above their hand. Koi will shove each other out of the way as they suck in the
food, and occasionally they’ll sample — and discard — your hand. Don’t worry,
it just tickles.
Using automatic feeders
Automatic feeders are one way to
make sure your koi are fed. These feeders work either on a timer or on demand,
where the koi nudge a pendulum on the feeder base.
For fry, the timed feeder is best
because they’re too small to activate the demand feeder, and they need food at
regular intervals. Timed feeders can be activated by solar panels (which need
only light, not direct sun), by spring-loaded built-in timers, by computer signals,
or by electricity.
Select the one that works best
for you (and for your budget). Adult koi seem to enjoy working the on-demand
feeders, and you can set the feeder
hopper to dispense a smaller amount of food upon each activation if you’re
worried your koi will make pigs of themselves.
by R.D.Bartlett and Patricia Bartlett
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