How big can the common goldfish get in a pond Size. When kept in small indoor aquariums, goldfish tend to stay about 1 inch (2.5 cm) to 2 inches (5.1 cm) long. Goldfish may grow larger if moved to bigger fish tanks, but they usually do not grow longer than 6 inches (15 cm). In outdoor ponds, and in the wild, goldfish can grow to about 14 inches (36 cm). Trending.
Can Fancy Goldfish Live In Ponds?
You can keep any type of fancy goldfish outside in a species-only pond during the summer if temperatures don’t regularly exceed ~85 °F/29 °C. The pond should have some parts deep enough to not freeze entirely; most goldfish keepers recommend a depth of around 4 ft/120 cm.