Who Gives A Fish Forums

I'm relatively new to aquariums and I had a quick question.
I've got a 65 gallon tank - 4ft long and 18 inches wide. Currently, it's home to 6 small green barbs, a medium-sized red-tailed black shark, and a small common pleco. They've all still got some growing to do, but the tank looks pretty bare.
I'm thinking of adding a krib to the mix - what do you guys think? Would it be compatible with my current stock? Should I stick to just one?
I don't want to overstock the tank, so I'm mostly concerned about compatibility. One krib probably won't make a huge difference, but I want to make sure it's a good fit.

I've got a 60 gallon with a male and female Krib, along with 8 Tiger Barbs and a Feather Fin Synodontis cat - all seem to be getting along just fine. The Tiger Barbs pretty much ignore the Kribs, which is nice to see.