Procupine puffers can grow to about 17 inches so a 55 is way to small. If you badly want a puffer get a valantini puffer. They are about the only puffer you can do for a 55. Valantinis only grow to 3" from what I have heard.
Is a 105 gallon big enough for a russels lion, a picasso triggerfish, a foxface rabbitfish, a snowflake eel, a dogface puffer, and possibly a majestic angel and a niger triggerfish?