I have a Blue Spot puffer in my 30 gallon reef tank. I didn't intend to put him in there but My Porcipine Puffer in my 55 was trying to kill him. I only planned on keeping him in there for a couple of days until I could set up another tank but I changed my mind. I have an Emerald crab and many snails and hermits...technically the puffer should devour these, but mine has showed no interest in them. Also, he seems to be fine with my corals, they all look great and he has been in there for almost six months. ***I am not really recomending this because every fish is different, but I have yet to have any problems. He even leaves my Starfish and Sea Apple alone. Spends most of his time picking through the sand. Its up to you but it is always a risk.