Breeding Goldfish

Goldfish cover a wide range of species, but they are all members of the generic family Carassius auratus, and have been bred by the Chinese, Koreans and Japanese. One of the difficulties for the amateur to breed this fish is that they can be difficult to sex. The difference in their gender is only apparent when they are in a spawning condition.
Goldfish are capable of breeding when they are a year old, but they are in their prime during their third year. Under normal circumstances, it is impossible to tell their sex until they have grown to 8cm. Therefore it is impossible to buy a small fish and be certain of its gender.
The process of breeding is induced by a change in the temperature of the water. Goldfish will breed at a temperature of 10-26ºC, but the optimum temperature to ensure success is 20ºC. To induce the fish to spawn you can either wait for more clement weather, or you can artificially and slowly raise the temperature of the water.
It is easy to spot when they are ready to breed, as the male has a ritual of a “spawning chase”, whereby he follows the female around and pushes against her abdomen, for several hours. This should occur if all the conditions are correct with a few days of the fish being brought together. The female, when she is ready will lay her eggs in batches, the first batch being the most fertile. She can lay from five hundred to a thousand eggs, so they will not be released all at once. The male will immediately fertilize these eggs by spraying milt on to them.
Once the egg laying is over the eggs should be removed from the breeding tank, and rinsed in aged water, which is at the same temperature as the water they have been released from. They should then be placed in a separate twenty gallon tank. However the depth of the water should not exceed six inches, as the pressure of the water inhibits their ability to rise to the surface.


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