My platy keeps getting into the filter...?

I have a small 1-inch platy, and I upgraded to a 55 gallon aquarium recently. My favorite fish keeps disappearing somewhere, and my mom says the filter is the only place she could be. But I think she's too big to get stuck in there! Well anyway, she does reappear eventually. I was just wondering if getting stuck in there is hurting her or not, and how can I protect her from going in there?