Ack. He may have not been dead Sati! The apple snails have a tendency to "hibernate"; kinda hole up in their shells and not come out for a while. Sometimes they even float! Best way to tell, for future reference, is to take a whiff (yuck) and tap the "foot" thats covering the opening. If its firm, the snail is alive. If its mooshy? Its dead (and then you don't have to smell it!).
From
http://www.applesnail.net/ :
My snails are inactive for most of the time. Am I doing something wrong? The temperature is OK and the fish seem to be healthy.
Apple snails are rather lazy animals, they only creep around if they need to. In other words, when they are hungry or want to reproduce themselves.
If they have plenty of food, they will show almost no activity (why should they?).
In the case this inactivity sounds familiar to you and you worry about their inactivity, just reduce the amount of food for a week and see if that makes any difference (also check them at night!).
Another cause could be low temperatures. Make sure that the temperature stays between 18 and 28°C (65-82°F).
Also there might be an activity difference between species as reported by H. Auer. His Pomacea glauca is being the most active, second in rank this Pomacea flagellata and lowest activity showed by his Pomacea bridgesii.
My snail is floating around for a day now. Is he/she dead or what? What should/can I do?
Well, apple snails can be very inactive for days (see answer above this one) and if they have a lot of air in their lung, they float (sounds logical isn't it?). Floating of an apple snail doesn't indicate that there is something wrong or that he/she is dead.
To check if the snail is alive, take it out of the water and see if you can get it moving by touching the shell door. If the shell is closed completely, then you can be sure that the snail is alive because once the snail is dead, the muscles are relaxed and the shell door stays at least partly open.
Another way to check the snails is by looking at the heartbeat (only possible with young snails and snails with a thin shell). To do this, keep the snail in front of a strong light source so the light shines through it and look at the heartbeat. Have a look at the anatomy section to see where to look for.
