i dont totally agree witht that. i have a valentini and he will only eat nass. snails but leaves all my other inverts alone( arrow crab, cleaner shrimp, tons of hermits,turbo snails.). but all puffers are different. the real problem is the size of your tank. it is just to small. the minimum size is 30 gallons. the only way i see it being possible is getting rid of all the fish in there and make sure you keep the tank extra clean. because puffers are really messy eaters and they produce a lot of waste.