Welcome to AA!
As for your stocking, I would not do Tiger Barbs. They should really have a 20 gallon long tank. Really the Danios should be in a 20 gallon long too, but since you have them, they should be O.K
. You might could do a school of Tetras, Rasbora, or smaller Barb. Just some examples: Cherry Barbs, Glowlight Tetras, Harlequin Rasbora, etc. You could do about 8 of ONE of these species and your tank will be stocked.
On a side note, always check here before you add fish to your aquarium. Even if AqAdvisor says it is okay, that doesn't neccessarily mean it is. I learned the hard way!