I have a female Endler Livebearer who has a bright red patch on her left side along her gills. It is only on the left side and was definitely not there yesterday. She moves so darn fast it's hard to get a good look at her but it almost looks like she's been bitten by something and a chunk of her scales are gone. She doesn't appear distressed but she definitely did not eat like normal tonight. She's swimming around the bottom of the tank rather than coming to the top and begging like normal. Tanks stats are: 10 gallon with river rock, driftwood, java moss, terra cotta pot Inhabitants are approximately 25 Endler Livebearers, 3 Panda Cory Cats, Red Cherry Shrimp, one Mystery snail 80* temp pH 8.2 0 ammonia 0 nitrite 10 nitrate Last water change with Prime was yesterday. My filter intake is baffled with a piece of panty hose rubberbanded over it. Most recent changes were yesterday, when I added some new RCS and she just had fry about two days ago. I am feeding crushed NLS Thera + A and small chunks of Hikari algae wafers to the corys/inverts. The pic isn't the greatest quality but it's the best I could get considering how fast she is. It's actually much brighter red in person than it appears in the pic. What is this and what should I do? I could net her out and move her into my 5 gallon, tho it's not done cycling. It's only inhabitants are 8 trumpet snails. If needed, I could move them out to medicate. The only medication I have on hand is Melafix but I could go to the LFS tomorrow morning if I need something else. Hopefully someone can help figure out what this is and what I need to do to help her.