yupp inch a mnth sounds about right =)
try wat kevinfleming21 said or mussels on the half shell you know wat will really work and is really healthy for them hell grow fast too well worked for me was frozen large hickari mysis shrimp the bag is abou $6.99 my puffer loves it i also feed him bloodworms,cut earthworms,clam on the half shell,mussel on the half shell,pond snails,apple snails,mystery snails,well all kinds of snails lol, mysis shrimp,live brine shrimp,tilapia, medium crayfish,fiddler crabs,sometimes ghostshrimp about a dozen of them, and wen i really want to see him behave like a true predator i throw in some neon tetras or platys their a lil more then feeder fish but healthier and less risk of fat or parasites =)
but i feed him every monday,wedsnday,friday and sunday once on that day so my water wont get dirty or leave a big mess in my tank that might put my water,plants or my puffer in risk