Care of Newly Hatched Koi

Monitor the eggs daily to anticipate the fry's hatching date. At a temperature of 68 degrees Fahrenheit, koi eggs will hatch within about four days. However, at hotter or colder temperatures, they may hatch as soon as three days after laying, or as late as one week. Watch for a shiny gloss appearance; this signals that the fry will hatch within a day or two.

Ensure excellent water quality before the eggs hatch. Your pond should already have a working aeration pump, which increases the amount of dissolved oxygen in your water. Check your water parameters daily using test strips. Your ammonia levels and nitrite levels should be undetectable at all times, and your nitrate levels should not rise above 30 ppm.

Observe your fry carefully after they hatch. For the first two to three days after hatching, the fry will adhere to the sides of the pond. During this time, they do not require food but are very sensitive to poor water quality. Perform partial water changes as needed to keep the new fry healthy. After two to three days, the fry will become free-swimming and will begin requiring food.

Feed the fry small amounts of live infusoria, daphnia or brine shrimp, which are available at your local pet supply store. Feed sparingly, offering only trace amounts of the foods three to four times per day. Note that overfeeding can degrade water quality.

Check water parameters daily for the first few days of your young kois' lives. A 20% water change can help to prevent poor water quality, but check to make sure that you don't inadvertently remove koi fry from your pond.

Feed your fry small amounts of powdered koi pellets beginning one week after hatching. A high-quality pellet food can supplement the young fry's initial diet. By the second week of life, the fry no longer need small live foods.

Offer your koi fry small, unpowdered pellets after they have attained a size of one half-inch. By the time they are an inch long, they can generally eat the same foods as their parents.