First I would start by adding water to the tank
and then I vote for puffers.
I am looking into them for my kids tank, and Lou's Pet shop has the best prices on them.
What kind of prices at Lou's and which species? I've never been there but would consider it if they have some of the more uncommon types.
Im not sure that the name is they are the green with black dots, They were$3.99, went to tropical treasure and they wanted $7.99 for the same fish
Green spotted puffers then most likely.
Pet Supplies Plus has them for $3.99, lots of other places they're $7.99.