Tropheus also take in lots of vegetation, in the form of algae and the tiny animals that live in it, in nature, so their diet is considerably different higher in veggies, than the more carnivorous fronts.
Since Tropheus are prone to stress induced bloat for a number of reasons (including the gluttony RD mentioned), feeding a more heavily vegetarian pellet high in the form of Spirulina would be my choice, and housing them with fronts that need more animal (seafood in the form of fish and invertebrate pellets) protein could IMO subject them to another bloat precursor as Tropheus cannot help but bulk up on any food offered, especially if housed with slow more dainty eaters like fronts.
Another case where multiple tanks seem needed, as opposed to one community of random individuals.
Add another stressor for Tropheus like not having the security other Tropheus of the same species around, increases the odds of a less than stellar outcome for the tank.