In my experience, absolutely. In fact, the yellow labs and Melanchromis you got from me came from a tank with four cobalt zebras (as well as Pseudotropheus socolofi and rusty cichlids (Iodotropheus sprengerae)).
Another fish you might consider would be Pseudotropheus acei, which I've been told tend to inhabit the upper third of the water column (all the fish in my 65g tend to stay in the bottom 2/3 of the tank). Similar size, temperament, and diet to your current fish, and nice blue and yellow color.