jus got 3 dwarf puffers.

Use a turkey baster, or just give them live food like brine shrimp or daphnia. Feed them at night if they're shy.

They are big enough to find and eat some surprising things! Try to get some little pond snails (if you go back to PETsMART and ask for some out of the plant tank they will probably give them to you for free) and keep them in the tank for the puffers to seek out and eat. Put a few adult size snails in there too, hopefully they will lay some eggs in there and give you a better supply of snails. They need to crunch the snail shells to keep their teeth from growing too long. Small ghost shrimp will be appreciated too. Also give them frozen fish food, they will not eat flakes. I wouldn't try to keep any other fish with them, puffers can be real mean and they aren't fast swimmers, but if they select another fish as a target they are persistent enough to harass it a great deal, plus their little nipping teeth can wound a fish.

Fish usually have a pretty good sense of smell, so finding it really won't be a problem for them. Thaw the cubes first so they have an easier time eating it.

Are they eating the krill? I think they might, I gave some to ours once and they ate it. You have a lot of room in a 10G for maybe 4 or 5 more puffers, but they might not all get along so well. Try adding new ones a couple at a time and see how it goes.

I have no puffers as of yet, but I have been toying with the idea of putting a couple in my 5 gallon when it becomes vacant. That seems like the ideal size tank for me to try having live plants. I've been afraid to try it because I've killed every houseplant I've ever had. I guess I just keep my house too dark. If the aquatic plants go the same way I won't be out a lot of dough since that little tank won't need a LOT of plants to make it nice.