Snail for a fry tank

I have 3 Platy fry in a bare bottomed 2 1/2 gallon tank with a sponge
filter. I read that snails can be put in a fry tank to clean up the
uneaten food. I have an apple snail a little bigger than a quarter,
can I add her? I am weighing between the uneaten food being eaten as
opposed to the added waste that the snail will add to the tank. I do
a 50% water change e/o/d.

On a similiar note, can anyone give me their experiences with Platies?
I have never had them, done much reading but they honestly sound kind
of boring, without too much personality. I'd appreciate anyone's
experiences with them.

As always, my thanks .