how big do goldfish get

Goldfish typically grow to sizes between about 4.7 inches (12 cm) and 8.5 inches, with many common pet goldfish reaching around 6 inches. However, under optimal conditions (large ponds, good water quality, ample space), some goldfish can grow much larger, up to 15-16 inches (38-41 cm), and very rarely even larger. The largest goldfish recorded measured around 19 inches (48 cm). Growth depends heavily on species/breed, environment, tank or pond size, water quality, and diet. Fancy goldfish varieties usually max out smaller, around 6-8 inches, while comet and common goldfish have the greatest potential to get bigger. Goldfish generally never stop growing but their growth rate slows significantly after a few years. Most pet goldfish fall within the 6-8 inch range in captivity but can attain much bigger sizes in ponds or optimal outdoor conditions.