I’ve been dealing with this ominous illness in my tank for what feels like forever now. It’s taken two of my platys as well as a sword tail. What happens is this: The fish start hiding for a week or so, then they come out, all frisky, but look awful and so so thin. They get interested in eating and seem to be feeling better, however, still so thin, and then a few days later I will find them dead. It’s very discouraging. My black Molly has been having issues with (what I believe to be fungus) on and off for a few months as well. I noticed a white patch on her yesterday morning and by the end of the day it had spread all over her body. She seems to be getting remarkably thin at a very fast rate as well. She is still swimming and very interested in eating. She just looks raggedy. I haven’t really noticed her hiding in the past few weeks, maybe once or twice, but nothing too serious like I saw with the other guys. In the past my Molly has always come back from this with little to no medication required, just water changes. However, this time the disease seems to be particularly bad. I treated my 46 gallon tank with 10 ml of api fungus (I think that’s the brand). I didn’t want to overwhelm the system but thought it be best to treat the entire tank. I didn’t follow the directions (5ml per 5gallons of water) because the green color it turns the tank always makes me worried I’m doing something wrong . . . My tank has been GREAT for the past month. Awesome parameters, nitrates at 40, a little bit high, but not too bad. The tank used to be kept at 84f now it’s been lowered (gradually) to 81f. Haven’t been able to take parameters and will not get to until tomorrow night unfortunately. Tank is stocked with: 5 mollies 6 kuhlis 3 platys 2 algae eaters 1 sword tail 1 ghost shrimp 1 mosquito fish Aside from recent shimmying from a couple mollies, and a platy swimming slightly off kilter from time to time (any idea how to help that?) everyone else seems to be doing great. There’s also a bubbler and five plants in the tank. It’s an established tank that’s been running since December. Should I change the media in the filter? I’ve only replaced one cartridge since setting the tank up. It looks clear and I’m so afraid to mess up the cycling that I’ve been putting it off. Thank you. Any advice is helpful and greatly appreciated. I’ll post parameters tomorrow night!