juicebox
Fish Fanatic
the 1-inch rule can be flexible. i'd say you're safe with getting 3 more barbs to make a small school. i'm sure it'll be entertaining to see them shoal together! 
what types of plants do you have? a black or blue background works very well with planted tanks; it makes the plant and fish stick out more. do you know what your watt per gallon is (total wattage divided by tank volume)? are you using any co2 diffusers, substrate, or fertilizers?
what types of plants do you have? a black or blue background works very well with planted tanks; it makes the plant and fish stick out more. do you know what your watt per gallon is (total wattage divided by tank volume)? are you using any co2 diffusers, substrate, or fertilizers?