Originally Posted by
smsimcik
How big are your 9 discus? I'm going to guess they are juvies. That's alot to keep in a 65 gallon tank. Are there any other fish in the tank? Do you have gravel substrate? What have you been feeding?
A 40% water change isn't going to help much. If they are juvies, you should be doing 80-90% water changes daily in that size tank. I'm going to stick my neck out and guess that you're not practicing good husbandry for the number of discus you have in that size tank. And now you have stressed discus that are breaking down and have succumbed to a systemic bacteria or protazoal infection. Not to mention gill flukes.
If you have substrate, you need to get it out or transfer your sick fish to a bare bottom tank. Start doing large daily water changes, keep up the salt if you like. It's not hurting anything. You probably need to be treating the tank with an antibiotic like Furan 2 or Kanamycin.
But having said that, from what you are describing, your discus may past the point of help. Sorry, wish I had better news.