I live in Orlando too, unfortunately there isn't that many stores around besides the usual suspects: Petsmart, Petco, PetSupermarket...
There is a store in Longwood called Fishy Business (its not great, but its the best one in the city). There is another one in Tampa (Marine Warehouse), its about 1:30min away;
They have a much more variety of fish and last I checked (last week) they did have a lungfush, about 10inch.
Good luck, let me know if you find someplace else...