Hi all. My dottyback has a big white spot on its back and stomach is looking pretty bloated, as if it's food is not digesting properly. He is the fish that eats the least, but still doesn't have problems eating. Any ideas what this could be? Is it very serious. Need to set up emergency QT. any ideas how to do it effectively. Help would be appreciated. All parameters seems to be in check. Nitrates a little bit high though. Not sure if that will influence anything. Added some photos to check. Other fish in tank seems to be fine.