Help my loved fish is sick

[OCDP]

UV Steralizer will not help you in this case.

I say just do what you have been recommended to do.

That being... water changes, make sure your salinity, and temperature match the tanks salinity and temp.

Do a large enough water change , say 30% maybe?

Feed the fish... keep it's belly full, this is always a good thing to do with a sick fish.. feed it.

Keep your water quality the best you can...