No, they are not really for communities. They are predatory fish. They will eat anything they can get in their mouths like small fish. And their mouths enlargen when they "fire" at prey so looking at the mouth closed is pointless.
If you have medium to large fish i think they would be fine. Such as gouramis and mollies. (Babies would be eaten).
They are a very cool and extremely interesting fish though. Maybe you could set up a tank dedicated to them.
The most common species, the south american leaf fish, monocirrhus polyacanthus, will take live feeders and nothing but live feeders. If they are driven to starvation, i dont doubt their ability to try and nip half a molly.
But under normal situations, mollies would be fine i guess.
Actually, its best to keep them in a species only tank because of their eating habbits. Chances are that it will not be able to get any food at all with other fish around, they're predatory, but not exactly fast eaters ... right pain to feed as well Species only tank I say