I have a pair of red firefish as well. I had 3 to start, but the smaller one was bullied and jumped to it's dead ... in the overflow, down to the basement into a 70 gallon sump and jumped out down there. They are known jumpers, but I also have a canopy on the tank.
They are a neat fish and I have them with other peaceful fish so they are not picked on. There is also a pair of Onyx Clowns and are not bothered by them. They will bolt into a hole in a rock that they establish when frightened and they will sleep in that same hole as well. I had the pair with a Purple firefish as well and they all got along.
They pretty much eat anything I put in the tank from frozen to flake to small pellet food.