Jumping clownfish?

[redrum]

I've had three Perc. Clowns jump into my over flow to my sump. Luckily I caught one before he went down one of my stand pipes. For the other two it was unfortunately too late. Needless to say I have now covered the opening with egg-crate and have not lost any since. These were all happy fish with no enemies. When I enquired about the very same thing at the LFS (are they known for jumping) he replied, "Their stupid fish". And that's as close to an answer as I ever got ...................