It's sheer good news he ate. If I were you, I wouldn't add the other fish yet. For the sake of the lungfish. The rasboras may seem harmless, but the angelfish would at least feel curious and try and bite him a bit here and there, looking like a floating log. If you already have the other fishes with you, give it a try, though you may want and keep a close watch. But the best would be to leave the lungfish on its own until it fully recovers and behaves like a sound South American Lungfish.
