Malaysian Trumpet Snails

Question
I have a 29 gallon freshwater tank, that I have had without incident for many many years. About a year ago,without my knowledge,I had some Malaysian Trumpet Snails hitchhike on a store bought fish. Although they have multiplied into numerous numbers, they dont seem to have any cause for concern. My question is...Just over the past 2 nights they have been crawling out of the tank and dieing on the fish tank stand. I have cleaned up approx. 15-20 snails each day. You can actually hear them drop from the tank to the fish stand at night. Do you know the rhyme or reason as to why the snails have decided to commit "suicide" now?

Thank you for your time.
Tracey

Answer
I would suspect that one of two things are going on... something in the tank water is irritating them and they are trying to get above water level or they are running out of food and looking for another food source.  If the tank is heated... you can try to check the temperature... snails are not as tolerant of temperature changes as fish are.  dave