I made a thread before this that has long since died, but now I have better info & photos to provide.
Few days ago I noticed my nerite getting real inactive and it looked like the body inside the shell had swollen, or something along those lines. I now have reason to believe I'm looking at a collapsed mantle or something similar. The fact she has been alive for almost a week with this tells me it may not be fatal and can be treated or mended, but obviously I'm a novice at this and there isn't a lot of information on the internet related to snail injuries.
Params are ammonia, nitrite, nitrate 0. 7.6 pH. 77 temp stable. I dose excel, comprehensive, iron & equilibrium for calcium supplement. I don't notice any severe erosion or issues with the shell, only the body.
Sometimes she oozes some white goop (shown in second image). I don't know what this is. It looks like snot.
I do have a very very minor pond snail (or some snail) infestation from plants. I only ever see 2-3 crawling around at any given time, and I never let them get bigger than the size of a.... tiny toenail before picking them out. I read that certain strains of snails like to crawl into bigger snails and eat them from the inside out. I don't see any indication of this being the case but if there are opinions I would like to hear them.
Here are the photos:
Those were from Friday. This morning she isn't hanging around the water line anymore and is down near her usual spot in the corner, and when she's underwater it looks kind of worse. I will upload more photos once my roommate wakes up and I can turn some lights on.
I'd really like some help. I know she's "just a snail" but I love her.