i have a porcupine puffer in my 75 with softies and SPS still yet to kill anything thats not given to him as food
but eighter way your tank is way to small for a puffer
if you get a bigger tank and decide to get one its up to you , just make surew you feed him enough so he wont mess with your cleaner crew and corals
hes in their with cleaner shrim and plenty of snails
i feed him unpeeled shrim for the grocery store so he can peel it and "grind: his tooth on it