How large do goldfish grow?
Goldfish grow larger than you might think. Most goldfish sold in pet stores are babies. Small “feeder goldfish” are usually about three months old. Adult comets typically reach 8″ (20 cm), although they can grow as large as a foot (30 cm). Fancy goldfish commonly reach 6″ (15 cm), and sometimes grow as large as 8″ (20 cm). There is a common myth that goldfish do not outgrow their surroundings. It is certainly possible to permanently stunt fish by keeping them in close quarters and filthy water, but is that how you want to keep your pet? Goldfish kept in properly filtered tanks with good water quality grow rapidly and their size is limited only by their genetic potential.
