Is thier anyway to make my goldfish grow quicker?

i have a 2 inch goldfish that ive had since March and he has only grown a half inch.....he is in a 30 gallon tank i know he wll out grow this and as soon as he douse im putng him in my pond. But should i feed him diffrent food? (i feed him Aqueon Goldfish flakes and every once and a while a blood worm.