Boulengerochromis and Frontosas are the biggest piscivorous African Cichlids. Emperors can reach 3' long and Frontosas in the 16"+ range... maybe larger if adequate space is provided.
My 400 gal houses a pair of wild caught emperors and a colony (22, 6m/16f) of wild caugth Kitumbas. The emperors are 20"+ and the largest Kitumba male is probably 14". I haven't measured them in a long time. They will be some of the largest blue Zaires in the hobby though, as I intend to keep them for the rest of their life.
man those are cool fishes.
are tilapias all african? just curious coz i've seen some monsters in ponds, but the biggest one i've seen was almost 2' caught from almost a salt water (it was in the river mouth over in indonesia). these guys can live anywhere i think