I have 8 goldfish in a 120 gallon pond. its about 6 feet long and 3.5 feet wide. i hear they can get huge, but the biggest one right now is just about 6 inches. how long do they take to get huge?
It really depends on what type of goldfish (koi, comet, standard goldfish or any of the fancy types) and also the available food, space and clean water. They will grow pretty fast if all their requirements are met, and they are huge mess makers so any filteration on the pond will need to be seen to on an almost weekly basis. I wouldn't look at adding any more goldfish to the pond and just these 8 grow up.