Well established tank, all chemical balances perfect, all other fish perfect. One snakeskin discus, Naobi, has changed from being the most gorgeous and dominant fish in the tank, to losing her color, her appetite and her dominance. She has a small wound on her body, that looks like an ulcer. She has also started to show shades of black. The fish shop said she probably had worms and that she would die because there was no treatment! A second opinion said it was an ulcer infected with bacteria and gave me sulphur pills to dissolve and add.
From the change of behavior and losing color, you know your fish is sick.
First you try applying Acriflavine solution with salt.
Next apply antibiotic (Tetracycline) plus salt for 5 days.