Puffer fish information

HI,
Does the dwarf pufferfish puff up like the big ones in the sea do?
I saw some at the pet shop and I want to get a couple (or more, but maybe some clown fish), my friend is giving me a 20 gallons aquarium. I'd also like to know if it is big enough,...

if they get along with other fish, and anything else that might be useful!! I know about the kind of water they need (half way between salty and normal water, and I also have a water heater, I've heard you have to feed them shrimps and stuff like that..anything else?)
Thanks in advance!

yea they do puff up but ceep anoying, curius children awey...if they puff to many times they become streest and they dye