Goodness. It's a juvenile Amphilophus. Most likely it's a midas/red devil that hasn't gone through a color change yet. Not a flowerhorn, and not a firemouth.
I bought this at a pretty reputable lfs, and it was labeled as a Firemouth. They had a bunch of them in the tank and they all pretty much looked the same. I have never seen a firemouth with red fins, and red eyes before. I searched all of the Thorichthys species on google and I couldn't find one that looks like this. Him and my firemouth were both flaring there gills at each other when I first put him in. But since then all is calm. BTW I just changed my water and I forgot to wipe the outside of the tank, hence the water marks.
How has mixing the CA/SA with the Africans gone for you?
Actually pretty good. Right now I have a 4"Texas, 4" firemouth, 6" jack, 6" venestus, 6" thicklipped, 4" female peacock, 2-2" haps, 2 plecos, a crayfish, and a 7" bullhead cat. In a 75. They all seem fine together with the only fighting being between the Texas, and firemouth. Most of them have been together over a year. I moved all my mbuna to the 55