When do fish lay eggs

When do goldfish spawn in the pond? | Reproduction & Propagation

Every beautifully designed garden pond invites you to let small goldfish swim in it. The first copies are quickly bought in the pet store. You can discover and conquer the home you have been entrusted with, and you can also settle with your own offspring. But is it enough that a couple willing to mate romps in the water and the time for reproduction has come? No, because the framework conditions for the spawning of goldfish must also be right!


Targeted creation of optimal conditions

In nature, every living being looks for the right niche in which it feels comfortable and in which reproduction succeeds effortlessly. Goldfish reproduce magnificently on their own if they live in a body of water that provides ideal conditions for them. But garden ponds are humid biotopes created by human hands. And the Carassius gibelio forma auratus, the scientific name of the goldfish, is its “unsolicited” resident. Some pond owners think too briefly: Fish and water, they go together. And wonder why no juveniles follow. You should quickly pay more attention to the following issues because they affect reproduction:

  • available habitat
  • the substrate
  • Protection and feel-good areas
  • optimal planting
  • Water quality
  • Food supply

Available living space

It is often underestimated how much habitat a small goldfish actually needs. Imagine your pond is the size of a bathtub. For how many goldfish do you think the amount of water is enough? For one, five or even more? Let's see what experts advise. For them, not all fish are the same, because it depends on their size and length. That's why they calculate the need per centimeter of fish. The following recommendations are given for the first stocking:

  • 60 liters of water per centimeter of goldfish
  • a 4 cm small goldfish therefore needs approx. 240 l
  • 2 fish per thousand liters are optimal
  • 5 goldfish should be the maximum in it

To come back to our example with the bathtub: With a capacity of around 200 l, only a mini goldfish can move in. If there are too many fish in the pond, the ecological balance will be permanently disturbed in the foreseeable future and further reproduction will be almost impossible.

The substrate

Ground goldfish. This means that they search the bottom of the pond for food with their mouths. That is why it is important to make it as natural as possible. Instead of a foil, it should consist of earth or gravel and some stones.

The bottom of the pond should also be at least 1.2 m deep in some places. Only in such a deep pond can this species of fish overwinter without any problems, because the water does not freeze over at the bottom. Otherwise it may well be that the entire goldfish population is suddenly destroyed after a very frosty winter.

Protection and feel-good areas

It is not only the depth of the pond that is essential for keeping and successfully reproducing goldfish. The pond structure itself should be divided into several levels of different depth. So the goldfish have different areas at their disposal, which they can visit alternately. Some areas because they feel comfortable in them. Others, however, because they offer them good hiding places and thus protection. This optimally structured habitat is the best prerequisite for the annual reproduction.

Optimal planting

Pond plants fulfill basic functions. Placed close to the edge, they shade the pond and thus keep the scorching sun out. The water cannot heat up. At least a third of the pond should be shaded in this way. With special aquatic plants for different depths, the different levels of the pond can be transformed into well-being and protection zones as intended. The animals find good hiding places from their predators under large-leaved specimens. But plants are also important for the following reasons:

  • they are a source of food
  • they filter / purify the water
  • the spawn can be deposited or adhere to them

Water quality

Anyone who ambitiously equips their pond with too many plants and too many fish risks poor water quality. However, this is important so that the pond life develops well in the long term and the reproduction works. A wet biotope as small as the garden pond is a shaky affair from an ecological point of view. Fluctuations in the decisive parameters can only be balanced out with difficulty or only slowly. The equilibrium can tip.

  • the planting is already doing a natural filtering work
  • a pond filter should also be installed
  • ongoing pond maintenance is mandatory

Goldfish are quite robust, but only when they reach a certain water quality do they begin to spawn. These are the ideal water values ​​so that nothing stands in the way of reproduction:

  • pH value: 7 - 8
  • Water hardness: 12 - 18 ° dH
  • Ammonium: <0.1 mg per liter
  • Nitrite: <0.1 mg per liter
  • Nitrate: <25 mg per liter
  • CO2: <20 mg per liter

The goldfish also needs certain water temperatures. In summer the water should be between 18 and 24 degrees Celsius and in winter between 6 and 14 degrees Celsius. However, there are subtle differences between the various goldfish species.

Tip: Perform a water analysis before stocking the pond with goldfish. If individual values ​​deviate from the optimum, the fish will not spawn. Therefore a correction is advisable first.

Food supply

Goldfish look for their food in the pond. They eat aquatic plants and aquatic organisms. In an ecologically healthy pond, the conditions of which meet the needs of these fish, there is enough of it. Additional feeding is usually not necessary. However, after each spawning, the number of goldfish increases. If the pond cannot feed them all, you can add suitable fish food in well-dosed amounts and in stages. Food that is not eaten by the fish within two minutes should be removed from the water with a net. Otherwise, leftover feed worsens the water quality considerably.

Tip: Find the optimal amount of food by starting with small amounts and observing. Gradually increase the amount until there are a few leftovers.

Goldfish spawning season

Only if all the aforementioned conditions and protective measures are met can offspring be expected at spawning time. The goldfish reproduce between spring and summer. It is known as spawning. During the entire spawning season of a year, approximately from April to May, the female goldfish can spawn up to ten times.

The courtship

When the water temperature has reached 15 degrees in spring, the goldfish are ready to mate. The female starts the spawn and gets a thicker belly. The male opens courtship by constantly chasing the female back and forth and nudging it again and again. After a while the female is exhausted and finally shows the challenged reaction. So it goes on:

  • the female lays eggs
  • approx. 500 to 3000 pieces
  • the male immediately fertilizes the eggs


Fertilized eggs are called spawning. The spawn looks like a caterpillar and has a silvery, shiny color. The sticky spawn clings to nearby aquatic plants and thus finds hold on them and protects them from predators. Therefore, suitable planting is one of the protective measures that make the goldfish possible to reproduce.

Hatching time

The leaves of the plants are a protective roof for the spawn. In and around the pond are teeming with predators that eat spawn as soon as they discover it. For example, dragonflies should have it on their menu. Therefore, goldfish will only actually develop from a small part of the spawn. Their hatching time is a few days.

  • hatched fish are tiny
  • each specimen is about 1-2 mm in size
  • they are initially colored dark gray
  • the color serves to protect against predators

Only after a year of life does the young fish shine in a golden sheen, to which this fish species owes its name.

The first goldfish days

The little goldfish first consume the nutrients they received for the beginning of their life. These are in a yolk sac that sticks to them. Then they have to go in search of new food. For them, only very small organisms come into question at this stage of development. When buzzing around in the pond water, they are welcome food themselves, for other fish species but also for their own big relatives. It so happens that few goldfish survive young age.

Protective measures

Anyone who would like to intervene after spawning to increase the number of surviving juvenile fish has two options.

  • create flat spots in good time
  • plant these densely
  • in it, newly hatched fish are safer from predators

If you own an aquarium, you can protectively intervene at an earlier stage in the reproduction process. Fish the fertilized goldfish spawn from the pond soon after spawning and add it to the aquarium. The little goldfish can hatch and live there without endangering their lives. They are only "released" into the pond after a year. In this they can in turn multiply.