How To Care For Cold Water Goldfish. If you live in a very cold climate or your pond begins to thoroughly freeze install a pond de-icer. Both begin dormancy at 64 degrees Fahrenheit and should reach a full state of dormancy at 44f.
The optimum temperatures for fancy goldfish is 68 to 74 F while comets and shubunkins should be held between 60 and 70F. Stop feeding at 54f. Goldfish owners should ensure optimal living conditions for their pets by controlling the water temperature.
In the winter its best to keep the temperature at around 55 F and slowly increasing the temperature to around 70 F over the following month.
Test water parameters. Making them live as long as possible the oldest pet fish is 45 years and still going strong. Under good conditions in a large tank some varieties can grow to 30 cm. The best way to promote the spawning of goldfish is to control the water temperature.