That's quite a small tank; 8 UK 9 US gallons according to the calculator on this site. I think it's too msall for danios; they're small but very fast swimming fish; they need a lot of space. You could try 2 male 3 female cherry barbs, or you could see if your LFS has some micro rasboras or tiny tetra like emebers; you could have 6 or 7 of one of those and some shrimp. That would be a nice little set up with some moss and branches