Every beautifully designed garden pond invites small goldfish to swim in it. The first specimens are quickly bought in the pet shop. They are allowed to discover their entrusted home, conquer it and, if they like, settle it with their own offspring. But is it enough that a pair willing to mate is cavorting in the water and the time for reproduction has come? No, because the framework conditions for the goldfish to spawn must also be right!

Creating optimal conditions in a targeted manner

In nature, every living being looks for the right niche in which it feels comfortable and where reproduction is effortless. Goldfish also reproduce magnificently all by themselves if they live in a body of water that has ideal conditions in store for them. But garden ponds are man-made wet biotopes. And the Carassius gibelio forma auratus , as the goldfish are scientifically called, their “unasked” residents. Some pond owners think too short: fish and water, they go together. And are surprised that no young fish follow. You should urgently pay more attention to the following issues as they affect reproduction:

  • available habitat
  • the ground
  • Protection and well-being areas
  • optimal planting
  • water quality
  • food supply

Available Habitat

It is often underestimated how much living space a small goldfish actually needs. Imagine your pond being the size of a bathtub. How many goldfish do you think the amount of water is enough for? For one, five or even more? Let’s see what experts advise. For them, fish is not just fish, because it depends on their size or 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 requires approx. 240 l
  • 2 fish per thousand liters is 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, just 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 ground

dig goldfish. This means they search the bottom of the pond for food with their mouths. It is therefore 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 hibernate without any problems, because the water at the bottom does not freeze over. Otherwise, it may well be that after a very frosty winter, the entire goldfish population is suddenly wiped out.

Protection and well-being areas

The depth of the pond is not the only important factor in keeping and successfully breeding goldfish. The pond structure itself should be divided into several levels of different depths. This gives the goldfish different areas that they can take turns visiting. Some areas because they feel comfortable in them. Others, on the other hand, 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 out the scorching sun. The water cannot heat up. At least one third of the pond should be shaded in this way. With special water plants for different depths, the different pond levels 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

If you are ambitious in equipping your pond with too many plants and too many fish, you risk poor water quality. However, this is important so that pond life develops well over the long term and reproduction works. Such a small wet biotope as the garden pond is ecologically a shaky affair. Fluctuations in the crucial parameters can only be compensated for with difficulty or only slowly. The balance can tip.

  • the planting already performs natural filter work
  • A pond filter should also be installed
  • ongoing pond maintenance is mandatory

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

  • pH: 7-8
  • Water hardness: 12 – 18 °dH
  • Ammonium: < 0,1 mg pro Liter
  • Nitrit: < 0,1 mg pro Liter
  • Nitrat: < 25 mg pro Liter
  • CO2: < 20 mg pro 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: Carry out 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 recommended first.

food supply

Goldfish look for their food in the pond. They eat aquatic plants and aquatic organisms. There is enough of it in an ecologically healthy pond, the conditions of which meet the needs of these fish. Supplementary 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 small doses and in stages. Food that is not eaten by the fish within two minutes should be taken out of the water with a landing net. Otherwise the water quality will deteriorate considerably.

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

Goldfish spawning season

Offspring can only be expected at spawning time if all of the aforementioned conditions and protective measures are met. Goldfish reproduction occurs between spring and summer. It is called spawning. During the entire spawning season of a year, around April to May, the female goldfish can spawn up to ten times.

The courtship

When the water temperature reaches 15 degrees in spring, the goldfish are ready to mate. The female puts on the spawn and gets a bigger belly. The male initiates courtship by constantly chasing and nudging the female. After some time, the female becomes exhausted and finally shows the challenged response. This is how it goes on:

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


Fertilized eggs are called spawn. The spawn looks caterpillar-like and has a silvery, shiny colour. The sticky spawn attaches itself to nearby aquatic plants and thus finds hold and protection from predators. Therefore, suitable planting is one of the protective measures that make it possible for the goldfish to reproduce.

hatching time

The leaves of the plants are a protective roof for the spawn. In and around the pond, predators swarm and will eat spawn as soon as they spot it. For example, dragonflies are said to have it on their menu. Because of this, only a small portion of the spawn will actually develop into goldfish. 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 juvenile shine with a golden glow, to which this fish species owes its name.

The first goldfish days

The little goldfish first consume the nutrients they received to start life. These are in a yolk sac that is attached to them. Then they have to go in search of new food. At this stage of development, only the smallest creatures are suitable for them. When swimming around in the pond water, they are welcome food themselves, for other species of fish but also for their own larger relatives. As a result, few goldfish survive to young age .

protective measures

If you want to intervene after spawning to increase the number of surviving young fish, you have two options to do so.

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

If you own an aquarium, you can intervene protectively at an earlier stage of reproduction. Fish the fertilized goldfish eggs out of the pond shortly after spawning and put them in the aquarium. The small goldfish can hatch and live in it without danger to their lives. Only after a year are they “released” into the pond. There they can in turn multiply.

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