Man I can't make that much water lol. It's a 240 gallon. I'll try whatever right nowExactly what I would recommend. Happened to me one time. Who knows what type of parasite or bacteria is chewing away at them fish, but now that it is all over the tank, might as well treat that tank as your quarantine now. I would do 50% water change every other day till conditions improve. I removed all of my substrate, rocks, etc. rinsed filter sock from sump daily! I cranked up the heat to 80F. Added new carbon in my reactor.(changed that weekly) and dosed with whatever my FLFS Recommend to treat bacteria, fungus, ick, etc. now a days there are quite a few
(API (2 Pack) Melafix Antibacterial Fish Remedy 16-Ounce worked for me
***Cross fingers! You have really nice fish man!
*It helped to put an air stone
*good water flow too.