Breeding Koi and Goldfish

Breeding Koi

Fish Sex

Preface

The following is an article written by Caroline Fish Putaansuu covering a presentation made for the Olympic Koi Club by member Bruce Lott in March of 2000. Bruce, spoke on how to breed fish, primarily goldfish, but also did a lot of research on how it correlates to koi. Bruce has years of experience in breeding and raising goldfish.

If you want to breed koi, there are several basics that you need to know in order to get started. Select healthy fish of the variety you want. Although you might want to begin a new variety of koi, I suspect many of us don't know enough Japanese to properly name them.

Fish Conditioning

Koi males should be 3-5 years old, 4-6 years is the prime age group for females. Condition them for one year. Make sure they are healthy and well fed. Put them through a hibernation cycle where feeding is stopped for several months. When it is spring, "love is in the O2" for fish.

Bruce says a menage a trois is what it takes. Two males to every female should be placed in the "spawn pond" or tank. This separate area is needed to ensure genetics. When asked how to tell the difference between male and female fish, it became a hands-on presentation when Bruce scooped a male goldfish out of his tank to show the spots on the pectoral fins.

The males will develop spots, not only on the pectoral fins, but also the gill covers. They are little white spots that feel like day old beard. You may notice them chasing the females (they'll also chase males), or rubbing the female's side with their heads. This inspires the female to spawn. Females have bigger abdomens (no jokes, please) and when they are full of eggs, are notably softer.

Setting Up the Location

The fish then need several things to spawn: a place to lay their eggs (media), privacy, proper pond temperature, and water quality.

Media for goldfish can be yarn, attached to a cork that keeps it suspended in the water. For koi, there are many options, not all of them listed here. Evergreen branches can be tied together and suspended. You can grow grass on the bottom, and re-flood the pond. There are artificial media like PVC pipe with nylon rope attached and frayed.

The fry need a place to hang out when they are first hatched, literally. They cannot swim yet, so they need an area to be safe and secure. When selecting media, this needs to be considered.

Spawning temperatures for both goldfish and koi is in the upper 60s and low 70s. The eggs' incubation time is inversely proportional to this. You don't want it too high (they mature too fast and have mutations), or too low (they mature too slowly and have mutations). Bruce says sixty-eight degrees is optimal.

The breeding pond needs to have good water quality. A "springtime" effect prompts fish to spawn. Good aeration and O2 are needed. Remember the size involved here, a very fine mesh will be needed to avoid sucking small fry into your filter. After the spawning is done, an aggressive water replacement is needed. Your nose will let you know.

Most fish will spawn in the morning, between dawn and 9 o'clock. If they are disturbed, this can stop them from "doing the deed."

The Eggs

The eggs are really sticky, and will adhere well. Don't be too worried if the eggs start to grow a fungus-like substance. There are a lot of good eggs in there, too. Good eggs will be translucent. It's the unfertilized eggs that will be white and starting to grow fuzz.

At this point, remove the eggs or the parents from the pond. Eggs and fry can be eaten if you don't have them in a separate area.

The Fry

After they hatch, go 3-4 days without feeding them. After that, they require a good food source. Bruce prefers natural foods like daphnia (a fresh water crustacean which can be found in local ponds), or brine shrimp (the kind you buy in the store is too big, so you need to raise them yourself). It is a lot of work, but pays off. If you need an interim food source, boiled egg yolk will suffice. Bruce says it is like eating sugar for them. They love it, but it isn't the best. Plus, it contaminates the water.The temperature for growing fry should be 70-75 degrees.

Start culling at one month. This is where experience is needed. With goldfish, for example, Bruce was told to keep the dark and throw the white. For reasons only known to Bruce, he kept some white, and realized that those goldfish had the best colorations. Bruce culls out at least half of the goldfish at this time. Cull again after an additional 2-3 weeks. As they get older, give them more high protein foods.

Breeding and raising koi can be an art form. Understanding the basics is only a part of the equation. However, if you get the yen to breed your koi, don't hesitate to ask Bruce or Ed Fujimoto for tips and techniques.

Koi Story 2:

Last year, John Tibbetts transplanted plants from his old pond to his new one. Unbeknownst to him, the foliage had koi egg stowaways. They hatched, and the small fry flourished in his new pond. This just goes to show that breeding koi can be easier than expected. Or is that unexpected?