I hade a filter tube brake on my fluval 404 and lost about 15 gals of a 55gal tank before I heard it leaking "what a mess". I have made new saltwater and refilled tank. Heated to same temp as tank water. But now my Yellow Tang has a solid white line in the center of him. I am not sure he will make it. Any idea what that line might be? Also should I leave the lights off to reduce stress? Thanks