Inactive Mystery Snails

[0_Infinite_0]

Three out of my four Mystery snails have been very inactive. They've all been in different fish tanks but are now all in a 5.5g so I could keep a better eye on them. One snail is absolutely huge and very active. The others, not so much. One did come out for a bit today and climb the sides of the tank. One snail will partly come out but just sits like that. I think he's been like that for a week now, but when I poke him (gently) he goes back into his shell. Are these other snails dead/dying? I've had them for a few months now and they mostly eat plant matter or fish food with the occasional algae wafer. I'm just wondering if I should get some new ones. There's also a Betta currently in the 5.5g but he doesn't really bother the snails.

 

[BettaBettas]

ive been having the same problem, check and see if your sulfur dioxide levels are high that was my problem and I had ALOT of it which I didn't know, and that was slowing them down.. now there really healthy