How To Breed Goldfish The Right Way – A Step By Step Guide (2021) is supported by our readers. When you buy through links on our site, we may earn a commission.

While owning goldfish can be lighthearted, pleasurable, and a lot of fun, learning how to breed goldfish is something else altogether. Indeed, when it comes to breeding any sort of fish, the challenges and demands are numerous. This is particularly true, when it comes to breeding goldfish.

Which goldfish breeding method is the best? What are you going to need to be successful? How long does it take to begin to see results? We’re going to tackle these questions, as well as others, in this overview guide to breeding goldfish.

Whether you plan to do it for profit or for pleasure, there are several things you’re going to want to keep in mind.

From controlling your spawn, to raising your fry, here is everything you need to get going.

Getting Started With The Right Equipment

There are two notable breeding methods that we’re going to touch on. One is known as the natural method of goldfish breeding, while the other is known as hand-breeding. Each method has their own particulars and challenges.

Before we break down what you need to know about these methods, let’s take a look at the essential equipment every goldfish breeder needs to begin:

The Main Space

This should be a large tank. We would suggest starting in the 50-gallon range, but you may want to consider something even larger. You will also want to make sure this tank includes a good filtration system, the proper decorations, and everything else a standard tank needs to be functional and comfortable.

A Secondary Tank

The main aquarium is only the beginning. You’re also going to need a nice, comfortable tank in which to raise your fry. This tank should be around 10 gallons or 20 gallons. Nothing larger than that should be necessary, particularly for a beginner.

(Looking for the best goldfish tank? )

A Heater

There are a number of different options available to you on this front.


We touched on this above, but it is worth emphasizing. An emphasis on live plants is best. Hornwort is a good example. Silk plants and plastic plants are other options that you can explore.

Sponge filter

There are several possibilities for both the 10 and 20-gallon tanks we discussed. You’re going to need this for the fry tank.

Air pump

This is another essential component for the fry tank. Research and choose one that you think will suit your needs.

Spawning Mop

This is entirely optional. This DIY goldfish spawning device is designed to fulfill the role of plants, in terms of catching and keeping the eggs safely. You will want to decide for yourself if one of these is necessary.

Finally, of course, you’re going to want male and female goldfish, as well. You want goldfish who have reached their sexual maturity, which is around one year old. You also want to know how to sex goldfish for breeding correctly. This is one of the aspects of goldfish breeding where things can get a little bit tricky.

How To Sex Goldfish For Breeding Purposes

If you only have room enough in the tank for a single pair of male and female goldfish, that is fine. Some like to hedge their bets with a few males and females. This is fine, as well, provided you have a large enough tank to accommodate all of them comfortably. You should also try to keep more males than females, as this will increase the odds of successful mating.

The challenge on your end is to sex your goldfish correctly. Otherwise, obviously, you aren’t going to get very far.

Sexing is difficult, but generally not beyond these simple measures:

Body Shape

While not reliable solely on its own, this measure can nonetheless move you in the right direction. Female goldfish generally enter their breeding age, their bodies become heavier, plumper in appearance. Males as a rule do not gain weight in this fashion. They are more often than not on the slimmer side. Females also can look from asymmetrical than males when viewed from the top of the aquarium or pond.

Breeding Stars

Made from very small tubercles, which are small, roundish growths that appear on both plants and animals, these little white dots are well worth seeking out on your goldfish. These growths are made from the same materials as what makes fingernails and hair. When a male is ready for spawning, these dots are going to be easy enough to spot on the scales, pectoral rays, and gill covers. Females can have these spots, but this is considered to be an exceptionally rare event.


Also known as the anus, the vent of the female will start sticking out a little bit, as opposed to the male, when it is ready for spawning. The appearance will be similar to comparing two different belly buttons.


This is perhaps the most important, or at least easiest, indicator of whether or not your goldfish are ready for breeding. The males will start chasing the females around the tank. You will notice this when they start shoving their heads inside the tails of the female to shove them all around the aquarium. It is not uncommon to see multiple males in pursuit of a single female.

How Do I Get My Goldfish Ready For Breeding?

Once you know for certain that they are in the breeding period, and once you are confident of their respective genders, you can get them ready for the actual breeding process.

Females must exert a massive amount of emergency for spawning. Males do, too, but the demands are particularly substantial fore the females. They are going to need to bulk up to build enough in the way of fat reserves to be able to withstand producing eggs and milting. Before you actually begin to initiate spawning, you will need to spend approximately six months on the conditioning stage.

The transition from winter to spring in nature is what triggers the spawning behavior. If you keep them in a pond, you will want to keep an eye out for some of the indicators we mentioned above. If you are keeping them in your aquarium, you are going to want to start recreating the winter/spring transition. This is where the heater becomes handy. You’ll want to get the temperature in their tank up to around seventy-five degrees Fahrenheit.

When It’s Time To Actually Breed Your Goldfish

At this point, you are now ready for the actual breeding. This is where things can get particularly challenging. It is very easy for the whole thing to go south, and to find yourself being made to begin the work all over again. Any goldfish breeding expert will tell you that this is a trial and error process. Sometimes, it simply doesn’t work out.

Having said that, you are now at the point in which you can determine which breeding method is going to suit your purposes best.

We’re going to cover the basics of each. As you decide the pros and cons of each, make it a point to do additional research that breaks these methods down step by step.

How To Breed Goldfish: 2 Proven Methods

First things first: Make sure you have the additional tank on hand to keep the fry in.

The two methods, as we discussed earlier, are known as the Natural Method and the Hand-Breeding Method. Each has its own strengths and weaknesses. For example, the Natural Method is going to rely on expected behaviors to a significant degree. It is perhaps the easiest of the two methods, but it stil requires a great deal of concentration.

You have to keep a close eye on breeding behaviors, as well as anything that may go wrong. You will also need to be ready to have the fry transported to your secondary tank. This is also the point in which you will need to make your own spawning mop. We highlighted this above, and it is not difficult to make by any means.

Then we have the Hand-Breeding Method. This method gives you considerably more control over the breeding process. However, as the name of the method implies, you are going to be required to take things into your own hands. This creates unique challenges that you do not find with the Natural Method. As you also may imagine, there are some similarities between these methods. Up to a certain point, there is only but so much you can do.

Here are some examples of when you may need to pursue the Hand-Breeding Method:

  • You only have one male, who is finding it difficult to locate your female.
  • Your window of time for breeding is a very, very limited.
  • The male is not as active as the Natural Method requires him to be.

These are all good reasons for hand-breeding. Furthermore, some simply like the ability to be in more control of the effort. Just keep in mind that all of this requires a delicate touch in the extreme. The same degree of impressive patience is also demanded. Perhaps, even more so.

Regardless of the breeding method you choose, your eventual goal is to find yourself with a 10 or 20-gallon tank full of fry. Caring for them and then culling them are your final two steps in this arduous, thrilling venture.

When It Is Time To Raise Your Fry

The eggs should be hatched in water no deeper than six inches or fifteen centimeters. Extremely gentle aeration is required, and the water should be maintained in the 70-75F range. Your eggs should begin hatching within two to four days. When this happens, keep in mind that you will not need to feed them for several days. This is because they can live off the yolk of the egg sacs.

Once they begin moving on their own, your fry are going to be absolutely starving. You will want to have fresh brine shrimp handy to keep them fed and happy.

Culling Your Fry

Understand that culling your fry, which is to eliminate the ones with undesirable traits, is NOT something that you are required to do. This is something that is done by those who are breeding for profit, simply because it is not cost effective to care for goldfish that no one is likely to buy.

Even so, particularly among those who breed goldfish for pleasure, some opt to keep whatever they wind up with. For many who go through the long journey of breeding goldfish, the idea of intentionally disposing of any of them seems unfathomable. The choice is ultimately yours to make.

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Jeff Colt

Jeff Colt

Hello, I'm Jeff- an aquarium enthusiast with over 25 years of experience caring for a wide array of tropical fish, including koi, goldfish bettas, cichlids and more! For me: Aquariums are like jello - there's always room for more!

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