Lyretail has gray, lifted scale(s) - picture attached

[BSej]

Given the length of time here, I don't think this is uronema - that typically kills fish very fast. I wonder if it is a spike injury from the tang? These can heal on their own, but if they get infected, the fish would need treatment with a broad spectrum, gram negative antibiotic in a treatment tank - Neomycin or Kanamycin would be two choices.

Can I treat in the food? Or does it need to be in the water in a separate tank? The lesion looks quite large.

 

[Jay Hemdal]

Can I treat in the food? Or does it need to be in the water in a separate tank? The lesion looks quite large.

Water treatment would be better, but you can treat the food, but it is very complicated to do correctly:

Proper Dosing of Medicated Foods

Proper Dosing of Medicated Foods Jay Hemdal c. 2020 Oral medications are an excellent way to target internal diseases of fishes. Marine fish absorb aquarium water, so in certain cases, they “drink” enough medication from the water to effect a cure. However, freshwater fish actively export...

www.reef2reef.com

 

[BSej]

Unfortunately he passed. There was no way to catch him for QT. Thanks for all the help guys.

 

[MnFish1]

Unfortunately he passed. There was no way to catch him for QT. Thanks for all the help guys.

Sorry-you should pay attention to the remaining fish
EDIT - I meant "sorry about the fish that dies" - and make sure there are not issues with the others.... (I'm not sure it was completely clear