Mystery snail questions?

I'm getting a mystery snail for my large aquarium. It has one calico fantail and one black moor. Neither is aggresive. Will they get along with he snail? Also I read that sometimes they can escape if there's an opening in th tank, and on the lid of my tank the is a rectangle opening that let's the filter in. But the opening is definetley big enough for the snail o get out. What can I do to cover it? I thought about ceran wrap, but I thought it might be dangerous if the snail crawled onto it.