Nothing like that ever happened to me (yet) but I'm sure it will someday. Magfloats are always amusing. The tilapia in my avatar is strong enough to knock the magnet off and its the xl on a 55g. My 3 year old daughter can't even pull it off. And my big henlei follows me cleaning the 500g because she likes the way the water pushes her or something? She will turn to the right angle and sit against the glass so the water like pushes her head and eyes down? Idk but it's like a massage for her I think.