I've seen few fish with missing jaws and still thriving. Sounds like the archer fish choose the easy way out. So no need to making any assumptions from now. I've seen few posters over exaggerated about things and no pictures till they posted the picture and the damages turned out its not very serious damages.Ehh,he said the fish's jaw was torn off....not just damaged,as you said,okay?..IT'S GONE!...and now,so is the fish itself.