To breed goldfish, feed the parent fish a high-protein diet three times a day, change 20% of their water daily and keep the temperature around 70 degrees during the day and 50 degrees at night. Once the fish breed, you also need to create a fry tank where the eggs can grow.
- Prepare the goldfish
Feed your goldfish three times a day to provoke their breeding response. Protein-rich foods such as daphnia, insect larvae, bloodworms and brine shrimp are excellent choices. You should also add vegetables and fruit to their diet to keep them healthy and prevent constipation. Change 20% of their water out daily to remove waste from increased feedings, making sure to add purifying conditioner to the new water before adding it in. Make sure to keep the water at the appropriate temperatures -- 70 degrees Fahrenheit during the day and 50 degrees Fahrenheit at night.
- Sex the goldfish
The only way to sex goldfish is during breeding season. Female goldfish grow plumper, while male goldfish develop white star-shapes on their gills and pectoral fins. It is normal for the males to aggressively bump and push the females to encourage them to lay eggs. Separate the males and females from one another for three days so that they become more eager to reproduce with each other. Make sure the conditions of the secondary tank match the conditions of the first. This becomes the fry tank after breeding.
- Breed goldfish
Reintroduce the goldfish to one another, making sure to maintain tank conditions. Make and add a spawning mop to the tank, so that the eggs can eventually be moved to the fry tank.