Goldfish Breeding

Goldfishes are one of the most popular breeds of aquarium pets and are always in demand. Fishes lay thousands of eggs at a time during the breeding season.

However, if the eggs are not eaten up by other fish and if most of the eggs are properly fertilized an enormous number of fry (baby fish) can be expected. 

But breeding and nurturing goldfishes can be often quite expensive and time-consuming. Many goldfish owners want to breed their goldfishes and nurture their fry by themselves. It may not be very easy but if done properly one can expect a tankful of young goldfish fry.

Breeding Process

The male goldfish have concave vents (the vents cave inwards) while the female goldfish have convex vents (the vents bulge outwards). To commence the breeding process the males and the females are first identified and then either two males and one female or three males and two females are introduced in the same breeding tank and given some time for adjustment.

Soon, the male goldfishes will begin bear a lighter tint around their abdomen which would signal that they are ready for breeding. While the abdomen of the female goldfish will look slightly enlarged. 

One can easily notice the males chasing the female(s) during the breeding season. The females drop their eggs while the males distribute sperm over the eggs.

All of this usually takes place naturally without any intervention.
However, one may also breed the goldfish artificially with hands. Hold the male goldfish and gently rub its abdomen to clear the sperm from its vent and then whirl the water a couple of times, repeat the same process as long as there is sperm left in the vent.

Then hold the female goldfish and apply light pressure on its abdomen pushing the eggs out of its vent then whirl the water once more, and repeat till all the eggs are taken out. Consider mixing the water gently to properly fertilize the eggs and conclude the breeding process.

Tank setup for breeding

Preparing a new tank for goldfish breeding is an important part of the process. Creating the right environment for the fishes to naturally breed may take some time as fishes need to properly adjust to the breeding environment.

But before the breeders are released into the new tank the owners must ensure that the tank is properly cleaned. One may also consider cleaning the breeders for additional cleanliness.

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Once the tank is cleaned creating a natural setting with props such aquatic plants and fibers helps the goldfish adjust quickly. But if one chooses to breed their goldfish artificially they need not invest in the aquatic plants and the like.

Once the breeders are introduced, cleaning the tank regularly is essential. One-fifth of the tank’s water must be replaced with freshwater daily to maintain the breeding conditions. 

Making sure that no leftover food is left decomposing at the bottom of the tank is yet another duty for the owners. With a clean and healthy tank, an optional natural setting, plenty of water and regular cleansing the right environment can be created for the breeders.

Breeding season

Like many species of fishes, goldfishes naturally breed during the spring. As the water temperatures rise with the oncoming of spring and with plenty of food goldfishes naturally prepare themselves for reproduction.

However, in a tank or an aquarium if the seasonal natural breeding is unsuccessful, goldfishes can also be bred artificially. The males and the females are identified by their vents from where they secrete sperms or eggs and then isolated in a separate tank and bred with hands.

Taking care of eggs

After the fertilization the breeders are taken out of the breeding tank as they may eat up all of the fertilized eggs. Depending on the temperature of the water the fertilized eggs take four to seven to hatch.

Ensuring the cleanliness of the tank is the only care one needs to take until the eggs are ready to hatch. Also, one must make sure that the water is not stirred or disturbed.

Creating the essential breeding environment for the goldfish, finding healthy and young breeders, initiating the breeding process and taking care of the fertilized eggs require a lot of patient effort and time but it is definitely worth the trouble.

Goldfishes are beautiful little creatures and the sight of a tankful of goldfish fry is more precious than all of the time and invested in spawning them.


[Revised and Updated for July, 2019]
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Written by Debra Hutchinson, founder of FishXperts