The winter management of goldfish directly affects the health of the fish and also impacts their adaptability, disease resistance, spawning time, egg production, and hatching rates in the following spring.
Cold Protection and Warmth Maintenance in Winter
For goldfish keepers, the primary task in winter is to ensure cold protection and warmth maintenance for the goldfish. In the cold northern winters, it is recommended to move goldfish indoors for care by mid-October. In southern regions, goldfish can be moved indoors based on local cold levels, either in mid-November or later.
Indoor Temperature and Feeding
When the weather is colder, the indoor temperature should be appropriately increased to maintain the water temperature between seven to eight degrees Celsius, and not lower than five to six degrees Celsius. At this temperature, only a small amount of bait should be fed daily.
Water Quality Management
In winter, due to lower temperatures, the water body is less susceptible to pollution or spoilage, and the consumption of oxygen in the water is relatively slow. Therefore, it is not advisable to change the water frequently. Generally, changing the water once every thirty days is sufficient, as long as the goldfish are not affected by the cold. However, it is still necessary to use a siphon to remove sediment from the bottom of the tank every one to two days and add some fresh water to increase the dissolved oxygen in the water. Special care should be taken when changing the water to avoid injuring the fish or stripping off their scales, as this can easily lead to fish diseases.
Wintering Over Outdoors
If there are a large number of breeding fish at home, it is possible to consider letting them winter outdoors. First, prepare an open-mouthed yellow sand tank or a slightly deeper ceramic tank, bury it in the soil by one-third to one-half, and choose a sunny location. The amount of water in the tank should be one-half to three-quarters, and cover it with a wooden lid and straw mat every night to keep it warm. During the day, the lid can be opened to let the fish bask in the sun, and on rainy days, a layer of plastic sheet should be covered on the straw mat to prevent rainwater and snow from seeping into the tank. Goldfish that winter outdoors can adapt to the variable weather in early spring and have strong disease resistance.
Original article by KPTer, if reproduced, please cite the source: https://www.kaipet.com/en/goldfish-winter-care-temperature-control-feeding-strategies
