Hmmm....big?
I know that doesn't help, but size really depends upon lifespan. The longer they live, the bigger some fish get, especially if given maximum amount of space to reach full size potential. I've seen some 10" blues recently at the LFS down the block from me. They were, well, bigger than I'm use to seeing 'em because I only get 1"-2" in my shop. Right now I've got a 1/2" female in my 20G that is soo small and tiny she's bottom of the pecking ordre for now. Even the Bloodfin tetras scare her, but I know that will change as she gets larger.
Fish size is usually given as a range, there is no definate on how big a fish will get. Again, that is all dependant upon nutrition factors, age of fish, size of environment, and how long it lives. At my shop, irridescent sharks are labled as only growing 8"-10", but as any true catfish lover knows, irridescent sharks at full grown can be at least two to three feet in length! Irridescents in the pet trade don't live much past 6" because people put them in their 10 gallon aquariums and the fish dies in four years because of cramped space instead of living the twenty to thirty it might normally in the wild.
~~Colesea