Hey!!! I had one of those, and then one day it died!! Couldn't figure out why! It was in with my guppies. I loved him. So they do this then? Just die? I wondered if I did something wrong.
I'm sure there's some underlying cause for it, but I could just never figure it out. I think it has to do with the pH being too low. Acidic water is bad for them because it dissolves their shells.
Actually, it's funny you mention them dying. After I changed the water two weeks ago, I noticed one wasn't moving. I wasn't sure that it was dead though. Then I finally realized it hadn't moved at all in two days, so I took it out and then ANOTHER died! I have a feeling it died because I didn't take the other one out right away. I was so sad! I feed them algae wafers twice a week and they gobble them up. I also change the water VERY often because it's a smaller tank. I just don't know what happened. Now I keep checking on them very often to make sure no others are dying on me! I'm down to five now. unfortunately I lost my blue and a dark purple :-(. Now I'm just waiting for them to breed!
I did some research on Apple snails becuase I didnt know what they were interesting facts:
These snails will "play dead" on occasion (especially when first introduced to a new tank, probably from the stress of moving from one habitat to another), even for several days, but once the snail is acclimated it will become a surprisingly active (albeit slow motion) participant in the community tank.
Nevertheless, apple snails are considered a delicacy in several regions of the world, and they are often sold in East and Pacific Asian markets for consumption.
Unfortunately, many species have a great appetite for aquatic vegetation and algae are not their preferred food. In such cases these scavengers can reduce the aquatic vegetation very quickly. They can ruin a beautiful aquarium within days.