Hi. Yesterday I noticed that one of my black molly fish has a badly swollen eye. It is white and sticking way out. The fish is still active and eating, but it sure looks awful. So far none of the other fish have the symptom. Do I need to add something to the water? I will quarantine it if recommended.
It's called pop-eye. Get an antibiotic to treat it. Mollies are also near brackish, if they don't have the extra salt. They will frequently get: finrot, fungus, pop-eye.