It depends if you want big fish or small fish and whether you plan on planting it, although it seems fantastically difficult given that the tank is 3ft high. If I were to stock it with bigger fish, as already suggest, perhaps 4-6 angels with a school of 50 neons... maybe discus. Smaller fish I would do 20-30 pygmy cories with a school of 150-200 chili rasbora.