I'm a owner of a comet goldfish, or better known as 'feeder fish', and proud to say she has grown to a dramatic size of 5 inches within a year. Comets are sold for around ¢25, but will never reach it's true lengths because of the ignorance of people who put them in flower vases or small half gallon fish bowls and think it's okay. Comet goldfish can reach the length of a foot! But by leaving the poor fish in a small bowl without any water changes and stunting the fishes growth, it'll end up dying within 6 months. So before you buy a comet goldfish or win one at a carnival, make sure you have the right tank for it. Don't be an ignorant asshole- fish matter too.