The Small Fry: Bringing Up Baby Koi

 In This Chapter

• Feeding the little buggers
• Culling: Population control
• Recognizing the best: Quality control

What can be cuter and more compelling than a group of 3-inch koi? At that size, they have a hint of the grown-up koi within. If you choose to buy them at this size, they aren’t expensive. All you need to do is keep them alive over a winter or two until you can see how their color develops and their body shapes up. Almost anyone can raise 3-inch koi.

If you have the space and the time, raising young koi can be a lot of fun, if only for seeing how they color, recolor, and shape up.

And that’s what this chapter is about — how to raise young koi, what to feed them, how to cull them (eliminate the weak ones), and finally, how to evaluate the success of your breeding program.

In a nutshell — or rather, in an air bubble — raising your koi is fun, but it’s also a lot of work and expense. (The food for the first two months runs about $300.) The task also requires that you cull over 99 percent of the young (although with 30,000 fertile koi eggs, you quickly realize that housing and raising even 200 young koi is a real commitment).

Feeding Fry

The appetites of older koi are easy to satisfy. However, newly hatched fry have very specific nutritional requirements and, because of their tiny mouths, their food must be in a size that they can handle. The foods in Table 15-1 meet their needs.

Fry live on their retained yolk for the first 24 hours after they hatch, but after that, their survival depends on you. You need to tread the fine line between providing enough food and not polluting the tank (because you can’t provide filtration).

The newly hatched koi need liquid or a suspended-particle food for the first day or so of life because they have tiny mouths. After a couple of days of this fine dining, the young are on a growth curve and are able to eat progressively larger, nonliquid foods.

Tip

Be sure you have all the necessary foods on hand when your fry hatch. You may not need all of them, but stock some of each so you can switch to another type if you run out of one food or if your fry no longer like one of them. The amounts in Table 15-1 are a good place to start, and you can tailor this list to fit your specific hatch size after you have some experience under your belt. If buying the different foods seems like a hassle, look for starter baby-koi food kits.

Foods for baby koi fall into three categories:

- Commercial foods: Those specifically created for baby fish, (such as liquid fry food) or foods for larger fish (such as blended freeze-dried krill) that you modify to be acceptable to tiny koi

- Live foods: Food such as baby brine shrimp that can be hatched from commercially available eggs

- Foods from your refrigerator: Foods that are part of a human diet such as hard-boiled eggs

Table 15-1                                                 Fry Foods to Have on Hand
Food	Amount
Liquid fry feeder	four dozen tubes
Brine shrimp eggs for hatching live brine shrimp	15 oz. can
Frozen baby brine shrimp	1.75 oz.
Powdered fry food for egg layers	50-lb. bag
Hard-boiled eggs	cook a dozen and use as needed
Fish flake food	1 lb.
Freeze-dried krill, powdered in your blender	16-oz. bag
Frozen daphia cubes	16-oz. package
Standard koi-food floating pellets, powdered in your blender	5 lbs.
Baby-koi sinking pellets	5 lbs.

A fry’s feeding schedule

Growing fish need quite a lot of food, but overfeeding results in leftovers that pollute the water. Although commercial koi foods are marketed as a complete, balanced diet, generally the widest variety of food as possible is safer.

The first month

During the first month, you want to feed your koi four times per day. The liquid food dissolves in the water and is available to the koi for some time after you introduce it.

Remember

Monitor your koi during feeding and fine-tune the amounts of solid food that they need. If you find leftovers at the next feeding, cut back on your volume (but watch that you don’t underfeed; large numbers of weak or dead fry are a sure clue). Only time and experience will help you gauge the right formula.

Add the new dietary items to each of the four feedings. Following are some tips and milestones for this first month:

- For Day 1, offer liquid fry food, one tube at a time. Simply squeeze the liquid food from its tube into the water. On this first day, also set up your brine shrimp hatchery. The specifics of setting up the brine shrimp hatchery vary from model to model, but all come with instructions and are simple to operate. Then again, you can use the production-line method we describe later in “Hatching brine shrimp.”

- On Days 2 and 3, continue to feed the liquid fry food, increasing each feeding to two tubes per feeding. Once a day, add a netful of newly hatched brine shrimp (see the section, “Hatching brine shrimp” later in this chapter). The koi prefer the live brine shrimp to all other foods, so leftovers are rarely a problem. Generally, you’re safe in feeding the daily output of your hatchery to your koi.

- After a day or two, your koi begin to associate human presence with food, and they wriggle to the surface of the water when you approach.

- For Days 4 and 5, continue with the liquid fry diet and newly hatched brine shrimp. Add 1⁄4 cup of egg yolk slurry (see the nearby sidebar, “Making egg yolk slurry” for the recipe).

- For Days 6 and 7, continue the diet and add the powdered fry food.

- During Week 2, add in frozen or fresh daphnia and koi pellets that you’ve reduced to a powder with a blender, a chopper, or a rolling pin.

- At the end of Week 2, discontinue the egg slurry and the liquid fry food. Replace them with fish flake food and ground krill (tiny dried shrimp).

- Continue with this dietary mix for the rest of the first month.

At the end of this month, the young should be 3⁄4 to 1 inch long. They are strong enough to swim against a filter current. Take these steps:

1. Turn on the filtration system.

2. Transfer half of the baby koi into a second incubator bin and make sure the filter and airstones are working in this second unit.

By splitting up the fish, you ensure better water quality and larger, more robust fish (crowding inhibits growth).

3. Cull your young koi (see “Culling: It Ain’t Easy, but Somebody Has To Do It,” later in this chapter).

As the koi increase in size, you can be a bit more selective in your culling — removing those that are weak or malformed, for example.

You may see some dramatic differences in the size of your young koi, even at the end of the first month. Some are cannibalistic, eating their smaller brethren. Net out these big pigs — discarding them or raising them separately — and continue this size-segregation netting monthly.

The second month

During the second month, continue feeding your fry four times per day. In general, feed as much as the fish can eat in about five minutes, but make sure that all fry are actively feeding during that time. If not, you’ll need to spend more time feeding them, or you can separate the larger fish. You can feed every food item in the following list at each feeding to ensure that all the koi have a shot at getting a balanced diet:

- Continue with the powered koi pellets.

- Replace the fresh brine shrimp with frozen (the shrimp in the frozen blocks are adult and much larger, but they’re easy to tear apart and consume).

- Add frozen daphnia to the diet.

- Depending on what brand of powdered fry diet you’re using, you may be able to switch to a larger particle within that brand.

- Feed baby-koi sinking pellets once daily.

At the end of the second month, your young koi should be 1 to 2 inches long.

The third month

During the third month, you can decrease the feedings to three times a day (stay with an amount per feeding that they’ll consume within five minutes or so) with the following changes:

- Offer the baby-koi pellets, powdered adult-koi pellets, and flake fish food.

- Cut the frozen daphnia to once a day.

Making egg yolk slurry Peel three hard-boiled eggs and separate the yolks. Mash the yolks to a paste with a fork and add water to the yolks, starting with 1⁄2 cup per yolk. You want the egg yolk soup to be liquid enough to use in a plastic squirt bottle (like a well-rinsed mustard or marinade bottle) or a turkey baster (nothing in the kitchen is sacred when you’re raising baby koi!). Store the egg yolk slurry in your refrigerator between feedings. Squirt a line of yolk slurry across the surface of the water in your baby koi bin, and watch the babies’ response. Because the fry are almost transparent when they hatch, you can see the yolk in their stomachs after they’ve eaten. Note: Egg yolk is almost pure protein, which, if uneaten, rapidly fouls the water and puts the koi at risk. Don’t dump the slurry in, willy-nilly. Feed a small amount at a time, watching carefully that the fry consume all of it. You can continue adding more, bit by bit, until the fish begin to lose interest. The standard rule is to feed what they can consume in five minutes or so, but adjust this to fit your specific situation. For example, you may have many nervous, slow feeders or many larger individuals that hog all the food.

Tip

Check the protein content of any food you offer your koi babies. They grow quickly and their protein content requirements are higher than those of the adults. Look for foods with about 40 percent protein content. Increase the protein content in your baby-koi diet if you see whirling (koi positioned head up, tail down in the water and turning in circles) or if cannibalism is rampant.

Remember

Monitor the water-quality numbers to make sure your protein skimmer and filter are taking care of the increased protein in the water. Even with the filters going, you need to make a 10 percent water change every week and remove the detritus on the bottom of the bin.

You can remove the detritus by one of the following methods:

- Sweep it toward the filter intake at the bottom of the bin.

- Siphon it up with a commercially available siphon. Most models come equipped with a rubber ball that is squeezed to fill the plastic siphon tube with water. Take care not to suck up any fry, and run the siphoned water through a net just to be sure.

Uneaten egg yolk contributes to the gray-green sludge on the bottom of your tank. This material sticks to the bottom and is difficult to dislodge with a net, so siphoning is the only way to remove it. Use a tall bucket to collect the garbage.

When you’re done siphoning, net out any baby koi from the bucket and return them to their nursery.

Flush the sludge into your wastewater system.

Hatching brine shrimp

Freshly hatched brine shrimp are minute enough even for koi fry. You can buy them frozen — a very expensive approach when talking about thousands of fry — or you can raise them.

Hatching brine shrimp is almost a mechanical process: Mix salt, water, brine shrimp eggs, and an airstone. Put a light overhead and wait 24 hours.

The best method for hatching brine is to have a production line. Set your production line up on a water-safe tabletop in your utility room, garage, or a protected spot on your porch. The table needs to be large enough for six water pitchers plus a bit of work space. You also need lighting for the area 24 hours a day.

You need these supplies:

• Six plastic 1-gallon pitchers
• 30 pounds of rock salt
• 40 ounces of brine shrimp eggs
• An air pump and enough valves and aquarium tubing to connect the pump to all six pitchers

Begin hatching three pitchers at a time using the following steps:

1. Put 2 1⁄2 tablespoons of rock salt in a pitcher.

2. Add water from your pond to within 2 inches of the top.

3. Add a tablespoon of brine shrimp eggs and stir to dissolve the salt and wet the eggs.

4. Put the pitcher on the left side of your table and add an airstone.

5. Follow Steps 1 through 4 for two more pitchers and set them along the left side of the table.

The next day, set up the rest of the water pitchers and put them on the right side of the table.

The baby shrimp, known as naupli, will hatch in 24 hours at 85 degrees F. (They take two to three days at lower temperatures, but keep them at a minimum of 76 degrees.) When the shrimp in the pitchers on the left side hatch, you have three days of baby brine shrimp. Pour the contents of one pitcher from the left side of the table through a fine fish net (this water can be discarded) and empty the net into your koi tank as one of the daily feedings. You can set up the pitcher with rock salt and a new dose of eggs, or you can wait until you’ve emptied all three pitchers and set them all up at once.

Culling: It Ain’t Easy, but Somebody Has To Do It

You have a lot of tiny koi when the eggs hatch, but the numbers diminish on their own, even with expert husbandry. (Some just seem to vanish, some get eaten by others, and some leap out of the tank.) But you’re still looking at lots of baby fish. At one-month intervals for the first three months, cull (euthanize unwanted fish or find new homes for them) your baby fish.

Remember

Although culling may sound cruel at first, reducing the number of baby fish puts the nose-count down to a manageable level, workwise for you, survival-wise for the fish left in your tank, and futurewise for trades or sales. The fewer fish you have to trade or sell, the more valuable each fish becomes.

Tip

Most breeders discard the culled fish, but other breeders dry them, grind them up, and feed them to the koi. That’s a little grisly for our blood. If you don’t want the young koi to die, at least not at your hands, ask a local pet store manager whether she’s interested in feeder fish. Instead of asking for cash for these fish, which the pet store may sell at ten-for-a-buck, see whether you can trade them for fish food.

What to cull

After the fish are showing color (about the end of the second month), you can cull for the colors you want. You may also wish to remove aggressive fry and those that are weak, stunted, or deformed.

If you’re breeding for Sanke (see Chapter Knowing Your Koi for a description of the various color morphs), look at the red-white-black koi in your tank. Discard the following Sanke:

- Those without red on their head.

- Those with red in the fins.

- Those that are more than one-third black — balance between red, white, and black is important for Sanke.

Also remember the following guidelines:

- Cull for solid colors; remove any solid whites or oranges.

- Keep all solid blacks because they may become Showa, the black koi with red and white markings. (On Showa, the red markings appear later, taking one to three years to develop.)

- Keep a young white koi that has red anywhere on its head because it may develop into a quality Tancho. (Large red markings on the head tend to shrink in size as the fish matures.)

A good Tancho (the white koi with the red marking on the top of the head) has a rounded topknot (the colored area on the top of the head).

How much to cull

Whenever you cull, you want to seriously reduce your baby fish inventory.

The following numbers are guidelines that generations of koi-keepers and breeders have used:

• The first month, remove and discard 85 percent of your fish.
• The second month, remove and discard 80 percent.
• The third month, remove and discard 65 percent.

If you started with 5,000 fry, at the end of three months you’ll have 52 healthy, lively, young koi that are 3 to 4 inches long. That’s still a lot of fish. However, if you started with 20,000 fry and culled for three months, you’ll have 210 fish, all of which eat, churn out ammonia, and grow about an inch a month. That’s too many fish. Keep culling until you have a number that you can manage properly, given your constraints of time and space.

Remember

There’s nothing wrong with being very selective about which koi you save; the singular purpose behind this entire adventure is to end up with a few very good koi.

Evaluating Your Young Koi

Deciding which fish to cull or show is a tricky process that becomes easier with experience. When your fish get large enough to seriously evaluate, keep this backwards rule of koi-judging in mind: Koi judges don’t look for what makes a fish pretty; they look for the flaws, or rather the absence of flaws. Check out the sidebar “How the pros breed (and cull) their fish” for more about this refined koi selection.

An experienced koi breeder knows all about potential flaws and how to pick out the fish with the fewest flaws. Because this process is a bit more difficult for a beginner, follow these steps:

1. Start with body shape.

A koi with a long back and a wide head is a good koi.

2. Move out to the fins.

A koi’s pectoral fins should extend well away from the body, with the rays fanned out.

3. Check out that skin! 

Any white skin should be bright and unsullied. Any colors atop the white should be dense. The edges of markings should be distinct, and the color of the markings should be intense.

How the pros breed (and cull) their fish Those who breed koi for a living have a more business-like approach to the process because they’re selling lineage, not just pretty fish. In Japan, breeding occurs in late summer. A female is placed in a spawning tank with a male, and they’re both watched carefully. When the female koi begins to scatter a few eggs, she’s removed from the spawning bin and anesthetized. She’s then held over a stainless steel bowl and dry stripped (her abdomen is gently squeeze-rubbed to strip her eggs into the bowl). These eggs are divided among a series of bowls, depending on how many males have been selected to pair with this female. (One male initiates egg laying, but several may actually contribute to fertilization.) Each male is anesthetized, and while he’s out of it, his milt (semen) is removed through his vent via pipette. The milt is mixed with Ringer’s solution, an isotonic solution that has the same salinity as fish blood, and each bowl is inoculated with one male’s milt. The eggs are gently stirred. Fertilization occurs and the micropyle (the opening in the egg’s membrane that allows for entry of the sperm) closes. The fertilized eggs are placed on spawning grass or brushes in a hatching bin, one male-female pairing per bin (so a few months down the road the breeder knows the success of each pairing). Water quality in each hatching bin is monitored for the next week and the infertile eggs are removed. After the fry hatch, they go into mud ponds, a growing-out pond. For fry, a mud pond is just 2 feet deep but may contain 44,000 gallons of water. A mud pond that large can hold 180,000 to 200,000 fry, the progeny from 6 to 15 select pairings. The young are fed infusoria (protozoans raised in cultures of hay and water), powdered food, and daphnia twice a day. At the end of the first month, the fish are from 3⁄4 to 1 inch long and the first culling occurs. The first cull simply nets out and discards 85 percent of the fry from the water. Some Japanese breeders dry the discarded fish, grind them up, and feed them to their brethren. A month later, the second culling removes 80 percent of the now 2-inch-long koi. At the end of the third month, another culling removes 65 percent of the remaining koi. What had been 180,000 fry are now 1,890, and they’re 3 to 4 inches long. Half of these koi are sold on the market. The remaining 945 koi are kept over the winter. The following summer, half of these almost-yearlings are sold. The remaining 472 go back into a mud pond (one deeper than their first mud pond) for the winter. That second summer, the koi are 12 to 14 inches long, and they have a ready market waiting for them. Just for the record, 0.2 percent, or one-fifth of a percent, of the hatched fry stay with the breeder through two winters.

by R.D.Bartlett and Patricia Bartlett