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How to Breed Goldfish in Mid-Winter

For many goldfish keepers and breeders, mid-winter poses a perfect time to focus on fish breeding. Time off from work around the holidays gives breeders an opportunity to carry out the detailed process of preparing for breeding and encouraging spawning. Regretfully, goldfish do not naturally spawn during the cold winters, instead waiting for warm spring waters.

Luckily, breeding your goldfish in mid-winter can be done, thanks to instructions from an expert Ranchu breeder, Gary Hater (Cincy Ranchu) from Cincinnati, Ohio.

Beginning The Process Outside

In order to have your breeders ready to spawn in mid-winter, it is important to begin the breeding process outside while the weather is cooling down and the onset of winter is approaching. Outdoors, you should utilize a pond which is large enough that overnight air temperatures will not cause major fluctuations in the temperature of the water. In most climates, a pond between 100-200 gallons should be sufficient.

It is important to regularly monitor the pond’s water temperature. When it reaches 55F, you should begin withholding food from the goldfish. This signifies to the goldfish’s biological clock that winter has arrived with colder water temperatures and scarce food resources.

Moving Your Breeders Inside

The next step is to move your breeding goldfish inside, before harsh winter temperatures set in. This should be done when the water temperature ranges from 32F to 42F, leaving your goldfish in a relaxed, docile state.

Your fish should be brought in from the outdoor pond in 5-gallon buckets, filled with pond water and aerated with an airstone in the top 3” of the bucket. Do not feed or medicate the fish at this point, but slowly integrate water from indoor tanks to around 60%. It is important to have the air stone high in the bucket so as not cause too much current and stress the cold fish. As your goldfish acclimate to their new settings they can be moved into your indoor breeding tanks. At this point you can begin feeding the breeders with adult frozen brine shrimp or gel food. Avoid frozen blood worms until the fish are adjusted to the conditions and you feel they have their immune system working normally.

Begin with regular water changes twice a week and ensure your fish are adjusting well to the warmer temperatures. You should begin preparing for spawning a couple of weeks after moving your fish inside. Food, especially gel food with wheat germ, should be provided to the tanks two to three times a day. After around a week of heavy feeding, your breeding tanks’ water temperature should be raised to around 74F through the use of a heater. During this period, water changes should be done with water that is around 5F cooler than what is currently in the tanks. From here you should be prepared for spawning to occur over the following couple of weeks.

Breeding goldfish during the mid-winter provides the time needed for many breeders to be able to focus on the step-by-step process. By utilizing chilling, outdoor ponds, “shortening the winter” for your fish can be accomplished to encourage breeding. From here, bringing your fish indoors and slowly raising the water temperature and introducing an increased feeding schedule can bring on spring according to the fish’s internal clocks. By beginning this process in late September or early October, Gary is able to prompt his breeders to spawn over the holidays from the end of December to the beginning of January. For Ranchu breeders, this means that your stock is quite large by the late summer shows.


Gary Hater is a native of Cincinnati, Ohio. He is a professional biologist and has had a fish hobby since the mid 1960’s. He moved to goldfish into 1980. He also breeds Philadelphia, English and his own veiltails, and Bristol shubunkins.

Goldfish Club

Goldfish Society of Great BritainAmerican Ranchu Society North American Veiltail Association Blue Egg Phoenix Preservation Society

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