If you want to breed your pond fish, you should be able to learn the techniques fairly easily. Common pond fish such as goldfish and koi fish require little supervision or help in order to breed. However, if you want to assist in successful breeding there are some things you can do.
Step 1 - Increase Temperature
Generally speaking, pond fish will spawn spontaneously as they respond to cues from the environment.
Like many other animals, they will begin to spawn in the spring. The surest indicator of the spawning season is the increase in water temperature. If you’d like to promote early spawning, use a pond heater to increase the temperature to about 74 degrees Fahrenheit/23 degrees Celsius.
This generally induces spawning. Bringing smaller fish to an indoor tank accomplishes the same thing. Fish also respond to lengthening days.
Step 2 - Place Egg Media
The new eggs need a place to stick and hatch. If you provide some kind of media for them, they will be safer, and you’ll be better able to control their breeding. It also allows you to move the eggs more easily.
Use a cork with yarn attached, or suspend a string mop head over the pond. The dangling strings are good egg media. You can also use evergreen branched tied together and hung in the water. Artificial water plants are also an option.
Step 3 - Watch for the Eggs
Koi are more obvious about their breeding. According to koi breeders, the male fish butt the sides of the swollen females in an effort to get them to expel their eggs.
Goldfish are not as obvious, but you will note the male fish following the females around the pond and through the hatching media.
When the eggs are laid, they are sticky and clear.
Step 4 - Separate Parent From the Eggs
The parents of pond fish will eat their own eggs and young (called fry). Because of this, as soon as the eggs are laid, they should be separated from the parents.
This can be done in several ways. First, remove the adult fish to another pond if it is available. It’s safer to move adult fish than eggs, so this is the preferred method of separation.
You can also move the egg media to another pond. Be sure it is warmed to 67 to 73 degrees Fahrenheit. The pool does not need to be filtered because young fry eat the algae and plant growth in the warm pond.
If there are no other ponds available, the third option is to use a screen or mesh to divide the eggs from the parents. This division should be done soon after the eggs are laid.
Step 5 - Care of the Fry
For the first three days, the fry do not need to be fed. After that, feed them standard fish food. Pellets should be ground for the first month.
Experts recommend keeping the fry separated from the adults for up to a year to ensure survival.
As you become an expert at breeding, you can match koi males and females to produce certain colorations.