Fire cichlids and Mbunas
I did read somewhere that Mbunas will skin them alive. However, I have some Mbunas in my tank and haven't noticed unusual aggression towards the fire jewels. What I have noticed that is different is that the fire jewels seem to hold a grudge for a while.
I have one male Mbuna who is nipping every fish that comes near him because he's "in the mood" and doesn't want any other fish near his lady. Most of my cichlids get popped and dart off to another area. My larger fire jewel will stand his ground and go rounds with him (even though the Mbuna is twice his size right now).
Then last night, one of my red fin obliq males was chasing the other male back and forth across the tank. The one that was fleeing bleached his colors out and ran to the other side of the tank where the fire jewels are... and they all got along fine for a while (the aggressive male obliq was leaving the weaker male obliq alone for a bit). The fire jewels didn't care that he was there in the least. About 5 minutes later, the fleeing obliq (that had just been sitting there) got an attitude, darkened his colors, and bit the fire jewel... once! The fire jewel commenced to kicking the crap out of the obliq (even though the obliq is much bigger than he is) and ran him off. The problem is he that he ran to other side of the tank.. where the aggressive obliq attacked him again and chased him back to the left side of the tank. This time, as soon as he was in view, the fire jewel jumped him... and repeated to jump him every time he came into view for the better part of an hour (although he did not hit the other male obliq). You could tell he just had it out for the one fish that bit him for no reason.
With all of that said, mine are still juveniles and I can't accurately say how it will be when they reach adulthood. I'm hoping they continue to grow together and are ok or I'll have to re-home them.