Yesterday I purchased 3 dwarf puffers from my lfs and they said they de-wormed them. 2 are great they are eating and are fattening up. 1 however is skinny and only pecks at the frozen bloodworms. He is acting normally and is very outgoing. Always at the front of the glass. Should I de-worm him myself and what should I do to do this? Or is there something else I should do? Thanks.