Information on Breeding Tank Setup and Spawning
The hatched goldfish fry should be left alone for two days until their mouths develop and then fed fry food ever four hours for the first two weeks. Fancy goldfish breeds can be fed two or three times a day. Goldfish fry that are fed freshly hatched brine shrimp nauplii tend to grow fast and become more full-bodied. Algae is another good source of food for the goldfish fry.
For the best goldfish care, water changes and cleaning will be required to eliminate excess food and waste. Do two 25% water changes a week. Remove any dead fry or uneaten food by siphoning the bottom of the tank using an aquarium gravel cleaner. To clean the water when the fry first hatch add a sponge to the intake of the aquarium gravel cleaner to avoid sucking up any goldfish fry.
The goldfish fry will begin to develop fins and start showing color patterns. At this point, algae growth, if any is left will not be a sufficient food alternative. Begin adding microworms to their diet to keep them well fed. Feed the goldfish fry at least twice a day. Microworms can last several hours in the water as the fry graze on them. The best specimens are not always the fastest growing goldfish so It’s essential to allow the microworms to stay in the tank so all fry have a chance to feed and grow.
This is the time to examine the growing goldfish fry and select the best ones to keep and cull (remove) the others. Cull any fry with defects and only pick quality specimens. Additional separation may be required if the goldfish fry tank contains a mix of long-finned and short-fined goldfish. Long-finned fry grow slower and need special care. Feed the long-finned fry a mix of foods to help them develop their bodies (in balance with their fast growing fins.)
Continue a heavy and diverse feeding regimen of the goldfish fry. Eventually add a power filter when the goldfish are strong enough to swim in the current a power filter produces. Preform 50% water changes twice a week to keep optimal water parameters which are key to growing healthy goldfish fry. Continue to cull the fry but it’s best to let them develop more before deciding. It might also be time to place them in a larger tank or in an outdoor pond. An outdoor pond will help them grow faster, give them more food sources and help bring out their color. Around month 6, the best specimens should be selected. Only 1% of all the hatched goldfish fry will likely make the final cut.