Update: Sadly my royal died

This whole thing has been really horrible. I am treating my other tank with antibiotics as a precaution. I got my feeder fish from a LFS. I started breeding convicts for a while to feed my guys instead but it did not go well as the convicts kept killing each other. My remaining two clown knives both eat dry food so hopefully I have seen the last of this disease. Thanks so much for your emails and updates.