There is some research that shows that goldfish may be able to their size to the size of their enviroment. They apparently have these sensors which allow them to see how much space is aroud them. But this is of course controversal evidence, and Im not sure whether I agree with it or not - sounds a bit like something out of star trek to me. However, can I just add that even if it is true then it is still no excuse to keep goldfish in bowls.Originally posted by yashinfan
Well I think you're right in a way. My goldfish are probably 2" and 4" long, and my b/f has one that is a good 8" or more (it's HUGE!) Now, my fish when they are in the pond grow to the 4" size from the 2" when they were bought from the store. Obviously, if they were kept there they would not grow that large, and obviously my goldfish'll never be 10" because they live in a pond where they would be picked off if they were that large for half the year and an 8 gallon tank for the other half of the year. They aren't unhappy and don't get sick very often at all. So to me, I think that they do adapt their size to their environment.