If you got one, just becareful, don't put it into planted tank. They will just eat anything and everything.
I feed them will plant I got it from local lfs, cheap one lah. Everytime i scaping my planted tank, those extra plant, I will just throw it into for them. I also wen into the river to get some plant, but pls make sure you clean it to avoid any bacteria or parasite.
They also feed on vege, any type. I would suggest a green one. But the problem is vege got spoild easily and make the water cloudly and dirty. For those who have turtle, will have the same problem. So every time I need to take out those un-eaten vege.
Snails need calcium to keep their shell look nice and hard. Few source of calcium; green vege, sea shells and sand.
Then bout last few days, I found out they start mating and on the same nite, they lay eggs. They will leg their eggs above water level.
P/s good website about apple snails
http://www.applesnail.net