White cotton fuzz

[MeT+3]

Hi!
I’m hoping someone can help as we’re relatively new to aquarium keeping (9+months or so). We currently have 2 mystery snails. The larger brown one is about 1 1/2” long and looks bigger every day. The smaller blue one is about 1/2” long and seems to be growing at a much smaller rate, although has definitely grown since July when we got it. The last couple weeks, the blue one has been really sluggish and not really moving. I’ve checked him daily to make sure he’s not dead and have occasionally put him in a smaller dish to watch. Lately, if placed in the smaller dish, he’ll poke his head out, but not really move too much. Today when I checked on him, it almost looked like there was white cotton batting stuffed in his shell. He let me scrape a little bit away from the edge of his shell near his head, but it seemed really thick and sticky. Water parameters are all within normal limits. The shell looks healthy otherwise (no pitting or cracks). There is a cuttlefish bone in the tank, but the water is naturally hard as well. The other snail and fishes are all fine. Just this poor thing. I can’t seem to find any answers on what is wrong and how I help/treat him. Any ideas or help would be appreciated! TIA!

 

[Realpedro]

When I first got mystery snails they secreted a heavy white slime that looked sort of like a fungus. It's a slime secreted when the snail is stressed. Could be the snail doesn't like the water or is getting harassed in the tank. Also a small object could be stuck in the shell.

Never really seen snails get a fungal infection, though I'm not sure why they couldn't.

 

[Colin_T]

Pictures?

Test your water for ammonia, nitrite, nitrate and pH.

Do a 75% water change and gravel clean the substrate every day until we work out what is going on.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

 

[MeT+3]

Hi! Thanks! Ammonia 0ppm, Nitrate 20ppm, Nitrite 0ppm, GH 150ppm, chlorine O, KH 40ppm, ph 7.8. I’m going to do another water change and cleaning again today. Incidentally, I put him in an isolation tank last night and today is the most I’ve seen him move in weeks so maybe one of my female guppies is just harassing and nipping him?
I added a couple pictures and the white stuff looks a little more slime like today and not as thick.