Sorry, but I'm going to say that it's a resounding "NO". The first reason is that, although Firemouths are reasonably peaceful for cichlids, they can still get rather aggressive to other fish, especially when breeding or if they become territorial. The second reason is that I'm not a believer in mixing fish from different habitats, or different continents. Their mannerisms, diets, preferred water type; everything is different. Third reason: Leaf fish are strict carnivores, while Firemouths are omnivores and need a large portion of their diet to be vegetable matter. It's very difficult to feed each species separately if they share a tank. Either the Firemouths will get a too high protein diet, or the Leaf fish will get a too low protein diet. Fouth reason is that their water requirements aren't the same. While it's true that at the Firemouth's extreme low end of preferred PH, and the Leaf fish's extreme high end PH are about the same, the Firemouth will prefer harder water, while the Leaf fish requires very soft water. It isn't a combo I would try. Leaf fish are very cool, I agree, but I would recommend a species tank so that you can meet their very specific requirements.
someone else should chime in here soon
