Most of the fish you have shown us appear to mbuna of some sort or another. They may even be hybrids. These fish would not be suitable tankmates for shelldwellers.
The first fish I bought five years ago were from the mixed African tanks at Pisces. The more I delved into the hobby the more frustrated I became at not knowing what they were. Two weeks later I returned them and exchanged them for a named species. (It was a Melanochromis auratus) Great fish, but I found that I couldn't keep anything with it in my 20 gallon tank.
Five years and five tanks later, I now keep a pair of L. occelatus in my 20 gallon tank with a pleco and a couple of rainbowfish.
I would recommend you return these fish and exchange them for fish that you will be certain of their origins. . Best of luck with your new tanks.