How To Breed Goldfish Successfully

Pond set up for spawningPond set up for spawning

Here we discuss the final steps on how to breed Goldfish now that your parents are properly conditioned, the weather is warming up, and everything is ready for your Goldfish to spawn.

To start from the beginning, click here...

What To Spawn Goldfish In

There are two choices:

  1. An indoor aquarium of between 20-50 gallons depending on the size of the parents and how many fish you are intending to breed or
  2. A small outdoor pond of about 80 gallons.

Whether you use an aquarium or pond, it should be bare of rocks, ornaments and gravel to avoid spawning injuries and make it easier to clean.  The only material present should be the spawning mops or plants that will be used to receive the eggs.

The water level should be reasonably shallow as Goldfish move to the shallows to breed.  Again it depends on the size of the breeders how shallow you want the water, 8 to 12 inches (20-30cm) is about right.

Aquarium Or Pond...Which Is Best?

80 gallon fiberglass pond set up for spawning80 gallon fiberglass pond

There are advantages and disadvantages with both.

The aquarium has the following advantages:

  • Being a smaller water volume, egg fertilization rates are higher
  • You can control the water temperature more easily (with a heater)
  • You can observe your goldfish more easily
  • Males with poor eyesight (Celestials, Moors) are less likely to lose the female


Goldfish are less inclined to spawn indoors.  This is due to a number of factors such as light not hitting the aquarium at sunrise, smaller temperature changes and a confined area being more sensitive to pollutants.

If the fish don’t spawn reasonably soon after being introduced into the spawning aquarium, frequent partial water changes will need to be made.  A filter can’t be used in a spawning aquarium as it will cause too much water movement and filter out the males’ fertilizing milt.

The outside pond has the following advantages:

  • Goldfish spawn more readily in an outside pond because the water temperature changes are greater
  • Sunlight hits the pond sooner
  • The Goldfish probably feel more comfortable in a greater volume of water
  • Pollution caused by heavy feeding has less effect on water conditions.


  • The greater water volume reduces fertilization rates (use more males to offset this)
  • Males with poor eyesight can lose the female (use more males to offset this and fewer spawning mops where the female can hide)
  • The pond needs to be covered from predators.

I use small fiberglass ponds of 80 gallons as a good compromise.  I still have to go outside to see what the fish are up to, but my success with spawning outdoors has always been far greater than in an indoor aquarium.

The ponds are easy to keep clean as I don’t have them buried in the ground.  I can siphon them out, tip them on their side and hose them out.  Cleanliness is important.

Pond Or Aquarium Preparation

API Stress Coat Water Conditioner

All you need to do is ensure the pond or aquarium is spotless and free of any chemicals.  Fill it with clean water a few days before introducing the fish.

I would aerate the water overnight to clear it of chlorine.  If possible don’t use any chemicals to condition the water.  If your water supplier adds chloramine to the water, you will need to use a water conditioner to remove it.

When preparing my ponds, I lay clear plastic over half the bottom and up the side where the spawning mops will be secured.  Goldfish are egg scatterers and many fall to the bottom.

WARNING:  If you use plastic film to cover the bottom, use plenty of smooth flat rocks as shown in the image above to ensure the plastic is held down firmly.  Fish have a knack of getting  underneath it and suffocating.

I keep the spawning mops together with rings made from plastic air line.  I put four mops per ring.  I then tie these rings together, and finally secure the rings with string to the pond side so they don't get pushed around the pond.  I want them to stay in the same position during spawning otherwise eggs will be scattered all over the pond as the female chases the mops.

I would set up an aquarium the same way as I would a pond but I wouldn't use plastic film on the bottom if the aquarium is going to be used for raising the fry.  Any eggs that fall to the bottom will stick, so they can be flushed when the water is replaced.

What Causes Goldfish To Breed

Changing conditions that cause your goldfish to breed:

  1. The lengthening days of spring
  2. A change in water conditions
  3. When the water temperature reaches about 68oF (20oC)
  4. A low pressure weather system passing through.

Your goldfish’s hormones are affected by the increase in daylight hours.  These hormones start the production of eggs and milt necessary for spawning.  The actual spawning is triggered, or delayed by weather and/or water conditions.

When Is The Best Time To Breed Goldfish?

Spring is the best time to breed goldfish.  You want to breed as early in the year as possible to give as long a growing period as possible.  But not so soon as to risk a severe cold snap.

Breeding very early limits available food for your fry such as mosquito wrigglers.

Goldfish spawn when there is a change in the weather.  If the weather has been hot, followed by rain, they will often spawn the next morning.  If the weather has been cold, a rise in their water temperature will cause them to spawn.

By placing the breeders in new water, this is often enough to induce them to spawn, regardless of the water temperature.

I have had fish breed in late winter with a frost outside when I brought them inside for a few days. The spawning was very light and not worth keeping.

How To Breed Goldfish - Putting the Breeders Together

After the water in your aquarium or pool has conditioned over several days, place the well washed spawning material into the pool or aquarium. (I use nylon spawning mops because they are easy to sterilize and don’t introduce water borne pests).

Spawning mopsSpawning mops

Goldfish are messy breeders, spraying eggs in all directions. Many of these eggs will miss the spawning material and fall to the bottom. As you do not usually use the same container you breed goldfish in to hatch the eggs, (unless it is an aquarium), I tend to make sure the spawning mops are long enough to reach the bottom of the container and cover a good portion of it as well.
Tie the mops together and secure them to one or both ends of the container. If you don’t they will move around and the females will scatter eggs from one end of the container to the other, with most ending up stuck on the bottom.

If a cold spell is on the way, delay putting the parents together because if they do spawn, there will be few eggs.

I tend to put the parents together mid-late spring, but always keeping an eye on water temperatures.

Introduce the parents into the spawning container the morning before you want the spawning to take place.  Hopefully, the fish are spawning the next morning.  Spawning activity is obvious because the male or males appear to be pushing the female around the pond or aquarium.  Every now and again she moves into the spawning material with the males in close attendance and releases some eggs.

Breeding activity starts as soon as sunlight hits the pool, and continues until about noon.

Observe any fish not participating in the breeding circus and remove them as they will eat the eggs.

The eggs are adhesive and the size of a pinhead when first laid.  As they take up water, and hopefully milt for fertilization, they increase in size.  After two or three hours they are water hardened.

After you observe that the fish have lost interest in breeding, remove the spawning mops to a temporary container (say a 2 gallon bucket) filled with the water the parents are in.

If you have limited time, remove the parents and untie the spawning material so it can float freely around the pond.  I would also place an air stone in the container.  This should be very temporary as the water will be full of unused milt which will quickly foul the water.

You should have a 15 to 20 gallon aquarium or something suitable filled with fresh aged water.  Make sure the temperature is the same as in the spawning container.

I now take each spawning mop, flush it in another bucket of the fresh aquarium water, and then place it in the aquarium.

This serves two purposes:

  1. It cleans the spawning mop of any waste material
  2. If the parents have flukes, the flushing hopefully removes them from the mops.  Flukes can wipe out an entire brood in days.

You now have your eggs safely placed in your aquarium, ready to start the next stage of raising your goldfish fry.

Knowing how to breed goldfish successfully is the easy part.  Knowing how to raise the best six to twelve fry to adulthood is a little more challenging.

If your goldfish don’t breed on schedule or after a few days, go to the When Spawning Doesn’t Go To Plan page for some possible solutions.

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