Our golden mystery snail hasn't been very active lately; she's* lying down a lot, with her foot mostly or 100% closed. I don't recall ever seeing her do this before, and we've had her about 8 months. I did a 40% water change to see if that would do anything, and she is still lying down most of the time. She does move, but rarely, and not too far. Water test before water change just showed some slightly elevated Nitrates. Water test 24 hrs after change cleared that up -- nothing else out of the ordinary. We have very hard water, so pH is very high as the norm, but it's never been an issue. Blue fantail goldfish, African dwarf frog, and 2nd snail are all seemingly doing fine. The only other abnormality is a small breakout of black beard algae on one of our moneywort plants. Could that be making our mystery snail sick or something?
*I'm not actually sure if this is a male or female snail -- we've just always referred to it as "she" 🙂 : Shelly.