Goldfish breeding in a pond: when do they spawn, how can you recognize it, and what should you do with the fry?

One May morning, the pond becomes agitated: the goldfish chase one another in all directions, splash near the plants, and jostle a female toward the bank. Don't panic, it's not a fight: it's spawning. In a healthy pond, goldfish reproduce every year without any help, sometimes a little too successfully. Here's how they reproduce, how to encourage it if you wish, and how to control it if your pond is overflowing with small fish.

From what age and during what period?

A goldfish becomes an adult at around one or two years old, when it measures approximately 8 to 10 cm. Reproduction is triggered by the combined effect of two signals: longer days and warming water. In practice, in our regions, the first spawning takes place between late April and June, often after a few days of fine weather that raise the water temperature above 15 to 18 °C. Several spawnings may follow one another until midsummer.

Identifying males and females

Be careful not to confuse the breeding tubercles of males, which are aligned and limited to the head and pectoral fins, with white spot disease, whose spots are spread across the entire body and fins.

The spawning process

Spawning generally begins early in the morning. Several males chase a female and push her against fine-leaved plants. She releases her eggs in small batches, immediately fertilized by the males. A female can lay several hundred to several thousand eggs. Transparent and about the size of a pinhead, they stick to plants, roots, and walls.

The eggs hatch in three to seven days depending on the temperature. The larvae initially remain attached and live off their yolk sac, then begin swimming and searching for microorganisms. They are brown or bronze: the red or orange color only appears after several months, sometimes a year, and some fish remain bronze all their lives.

Save the fry, or not

Adults, especially koi, readily eat the eggs and fry. In a pond without hiding places, very few survive, and that is often a good thing. If you want to raise them:

1. Provide spawning surfaces: fine-leaved plants or spawning mops.
2. Remove them after spawning, covered in eggs, and place them in a separate tank filled with pond water, with gentle aeration.
3. Feed the fry as soon as they swim freely: very fine powder several times a day, in very small amounts.
4. Return them to the pond when they are too large for the adults to swallow, generally at 3 or 4 cm.

What if the pond is overflowing with goldfish?

This is the opposite problem, and it is common in heavily planted ponds where fry find refuge. Overpopulation overloads the filter, raises nitrate levels, and encourages algae and disease. Solutions:

• Reduce hiding places during the spawning period to let the adults cull them.
• Capture surplus juveniles with a fish trap and give them to other pond owners or a specialist store.
• Never release them into the wild: goldfish are an exotic species that can disrupt natural environments.

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Frequently asked questions

— What is the goldfish spawning season?

From April to June in most regions, when the water remains above 15 to 18 °C. Several spawning events may follow one another until July.

— My goldfish are chasing each other aggressively. Should I intervene?

No, this is normal spawning behavior. A female may become exhausted or sustain a minor injury: hiding places and dense plants allow her to take a break.

— Why are my baby goldfish black?

Young goldfish are born bronze or dark gray. Their final color appears gradually during the first year, sometimes later.

— Can goldfish reproduce with koi?

Yes, hybrids sometimes appear in mixed ponds. They are generally sterile and do not have the qualities of a koi.

In summary

• Spawning from April to June, in water above 15-18 °C.
• Males with breeding tubercles, females rounder.
• Hatching in 3 to 7 days; the fry are bronze.
• For breeding: separate the eggs. To limit their numbers: let the adults handle it and remove the excess.

Last updated: September 28, 2026.