When I bought him he was very tiny, maybe 2". Just a baby. When I got rid of him he was about 7". He didn't grow very much for the time I had him, and I am sure that was due to the bad diet he was given at the time. I now know goldfish are not the food to give puffers, but like I said, 12 years ago, that and krill were all anyone would say to feed them in an aquarium.
When I got my second puffer he was about 4" but in 3 months grew to about 6" so I could definately tell the diet did make a big difference. BUT, the second puffer I had was nothing like the first. Not nearly as friendly and definately didn't seem nearly as happy as my first puffer. Because it was making us both unhappy, him stuck in the reef tank, and me losing corals and livestock to the puffer, I had no choice but to do the right thing and take him back.
That still doesn't change the fact that the first puffer always seemed "happy" in the first tank, would always play and seemed to LOVE attention. I put him in my 55G once I set it up and he hated it for some reason. I have no idea why but he would just sit on a rock and not move much. As soon as I put him back in the 29G tank he would be happy again. Strange sounding I know, doesn't make sense, but that was my personal experience. Anytime I would enter the room he was at the glass wagging his tail wanting to play.. chase my finger, eat out of my hand, let me pet him, and not once did he try and bite me (something that happens everytime I stick my hand in my current tank by my Maroon Clown).
Just goes to show the difference that 2 identical types of fish can have completely different personalities. I have had my fill of puffers for now. I still think they are the coolest fish ever, but I wouldn't buy one again unless I had at least a 240G+ tank. I did learn my lesson, actually, probably didn't because I did have success, but I do know the reality that they do really require a large tank and I wont be sticking one in a small tank again, nor would I feed them goldfish ever again.