The achilles i got from Divers Den and it was already 7.5". I think key is to get a healthy one but handling becomes a bit more difficult as they get larger, but i only have experience with the one. My MI has grown very quickly. Maybe quicker than any fish i've had. He eats a ton yet remains fairly lean. Mine was around 3" when i got him, probably about twice as big now. I think it's hard to find one less than 3". I feed him a big variety, hoping he'll get the nutrients he needs. I feed him angel formula frozen, live bloodworms, live littleneck clams, frozen spirulina, frozen mysis, NLS pellets (3mm), nori...