I Got Koi Fry – Now What!? A step-by-step approach to raising baby koi

If you’ve just realized that your pond now has a million little koi swimming around, skip to the feeding section, but if you haven’t raised koi yet and need an introduction, then read on.

Spawning generally occurs in the early summer months and is highly dependent on water temperature: 68 degrees F is the minimum for spawning. Your adult koi will need to be sexually mature to engage in successful mating and this usually occurs at 2 years for males and 3 years for females. When selecting parents, keep in mind that the larger the female, the more eggs she can produce. Typically, spawning activity and the behaviors associated with it will take place early in the morning and may last as little as 30 minutes. The whole process is a bit hard as the male needs to physically stimulate the eggs to be released by gently pushing on the female’s belly. After the eggs are released, the male fertilizes them by releasing sperm.

reproduction material

If you plan on having a dedicated spawning tank, you will certainly want breeding stock. This is simply a material that offers a surface area for the eggs to attach to. This could take the form of aquatic plants, rope, a “spawning brush” or a “spawning mop”. Most importantly, it should be something that is not toxic in any way and has plenty of surface area for the eggs to stick to. You will want to have plenty of breeding material for the eggs to attach to, perhaps around 50 to 60 percent of the bottom of the spawning tank should be covered. The size of your spawning tank will depend on the number of fish you plan to try to breed. It should be something on the order of 1 to 2 feet deep and maybe 6 feet by 6 feet; some hobbyists have used wading pools with success.

After the eggs have been laid and the adults have been removed from the spawning tank, you should see hatching around 4 days later. When you are satisfied with the density of the hatched fish, you can remove the breeding material.

Tank/Pond Requirements

You can choose not to go with a separate tank or pond for frying and just let it happen in the main pond. If this is the case, keep in mind that if you have goldfish among your adult koi, you will lose some eggs due to the goldfish’s appetite for koi eggs.

Your koi eggs will hatch around 4 days after they are fertilized. They will then cling to structures like the side of the tank or pond for 2-3 days, where they will feed on their yolk sac. If you are seeing a lot of koi fry swimming around and also a lot of eggs on the bottom, feel free to remove them as they most likely failed to fertilize and will only increase ammonia levels. Be sure to monitor all of the water chemistry, especially ammonia and pH.

What to feed your koi fry?

Around the tenth day (sooner depending on water temperature) you will notice that your koi fry are testing their newfound ability to swim and this is when feeding should begin. Many koi enthusiasts will start with something called “infusoria” which is not a thing but more of a size classification. It is generally defined as very small aquatic organisms and, for koi fingerlings, should be live daphnia (water fleas) and/or brine shrimp (“sea monkeys”). If you can’t get infusoria, you can try chicken eggs. Boil the eggs (some use just the yolks) and, in a blender, mix them with about 30 ounces of tank or pond water. Simply spray that mixture onto the surface of your breeding tank or pond. You will want to feed him around 4 times a day. In general, you are trying to match the size of the food to the koi fry so that it is the appropriate size for them to eat. After about a week of this mixture, you can switch to a powder called “fried powder” that can be sprinkled on the surface of the water.

You can also use standard protein infused koi pellets and basically grind them into a fine powder and select a certain grain size by shaking it through a sieve. It may take a few days for the fry to associate the new powder with food and acquire a taste for it. Be sure to clean the bottom of the tank for debris and excess/uneaten food; you really want to avoid ammonia buildup. Be sure to provide plenty of aeration for your koi fry and this is especially true in the summer when warmer water temperatures mean a lower oxygen carrying capacity of the water.

Some other foods you can feed are frozen brine shrimp, live brine shrimp growing in your holding tank or main pond, and freeze-dried krill. Spirulina powder and wheat germ can also be added as a nutritional supplement.

sacrifice

One mistake people make is trying to keep all koi fingerlings, that’s a bad idea. You will definitely want to “thin the herd” because doing so creates a healthier environment for the remaining koi. Your first culling round should take place around 1 inch or 25mm. This should fall about 4 weeks (possibly more) after it is first observed swimming. Another sacrifice should be made a month after the first or about when they measure about 2.5 inches or 6.25 cm. The first and second sacrifice should eliminate about 80% of the initial population. Also, a third cull should start a month after the second and remove 50-60% of what is left. When culling, you should look for deformities, undesirable coloration, erratic swimming, slow swimmers, and generally undesirable traits. You don’t necessarily have to put these fish down, give some to your friends!