I am totally lost on what to do. I have a sick black molly and I'm not sure if I should euthanize it or wait for it to die or treat it (if it isn't too late) and I think I have too many plecos. I have a: - 10 gallon freshwater tank - Aqueon Hang-On-Back/Power-filter - Heater - Thermometer - White and blue LED light - About 1 inch of various shades of blue gravel - 2 caves - 2 real plants - 4 bristlenose plecos that I feed with pleco wafers when necessary (about once every 2 days) - 1 sunset platy - 1 electric green glofish - 1 black molly I feed the 3 previously mentioned fish 3 times a day with Advanced Nutrition flakes for tropical fish. I also throw some shrimp pellets in the tank once a week to change things up a bit. I vacuum the tank about once a week. In february, I set everything in the tank up and let it run for a day, then my friend gave me 4 baby bristlenose plecos because hers had babies. I put those in the tank and they were fine - maybe a bit reserved; they hid a lot. Then a month later I went out and bought fish that would swim around more rather than just sitting on the bottom. I bought 3 that looked cool: the glofish, molly, and platy. After putting those in the tank, the plecos began swimming outside more and everyone seemed to be doing well. Today is the 22nd of April, and on the morning of the 21st I noticed that the black molly didn't come up to eat in the mornings, it was bloated and its fins were sticking out, and it just sat on the bottom of the tank. It was fine on the night of the 20th. I am quite new to taking care of fish, so I assumed it was something that would pass, so I left during the day and when I came back home about 8 hrs later it was still like that. I did some reading online and I think it is suffering from dropsy. I vacuumed the tank out which was covered in poop, mostly from the plecos, and refilled it with water of the same temperature and plenty of water conditioner, but the molly still looks terrible. I think its back fin has also began to rot since the 21st. As I said, I'm not sure what to do with it now: from what I've read online, some people say euthanize it before it makes any other fish sick, some say wait it out, some say to cure it, and some say it's too far gone to cure. I'm also unsure whether or not I should take out some plecos in case those caused the water quality to get so poor. Please help! I've attached 1 photo that shows the scales sticking out and the bloating, and 1 of the back fin.