I'm going to be getting a group of Astatotilapia latifasciata and was wondering if they could be mixed with Pundamilia nyererei (Mwanza Gulf) without the fear of crossbreeding. I can have them separated if need be but it would be easier to be able to utilize the one tank for both. Of course I will separate them if there a good chance of them crossbreeding as that is the last thing I want to happen.
In theory you should be ok if all you are worried about is cross breeding. But you may want to make sure that the nyererei won't bully the latifasciata too much. Nyererei are really aggressive for their size. Just keep a good eye on that tank.
I maintained a colony of P. nyererei alongside a group of A. "Thick Skin" for several years without any issues with cross breeding. Both of the species you mentioned (nyererei and latifasciata) have fairly unique color patterns, so I feel that they should not confuse each other as being conspecifics.
It's not impossible that they may breed with each other, but I feel it is unlikely.