are those the only fish you have? do you want bottom dwellers middle, or top? for bottom i would get some corys or a bristlenose plec. you cold get some tetras maybe
Well most tetras can be a little nippy but as long as they're kept in a large group you will have few problems. I would go for a large group in your tank. Probably 8 members or more. Hard to advise on what to get as it's personal really and I haven't kept lots of different tetra species. Why not pop to see what your LFS has. Write down what you like then post here or better still in the Cyprinids, Characins and Atherinids forum.