Dwarf puffers really need to be in a tank by their selves. When they are little they will tolerate other fish but when they mature they get really aggressive. There are many post on here of people trying to keep them with other fish or other puffers and it leads to disaster. If you have a heavily planted 10 gallon, you can sometimes get away with keeping two. If they see each other they will fight. Sometimes you luck out and get a placid one but it is the exception not the rule. You can feed them frozen bloodworms from a long tweezers. You can also try earthworms (cut up), thawed frozen shrimp, ghost shrimp (live), mosquito larvae, and the brine shrimp but rinse the salt off first. Here is a link to a forum all about puffers thepufferforum.com Great site for research.