It is a sad fact that many of us lose fish this way - several species are known to jump, which is why it is important to always research the fish you buy for your tank. However even when you have researched, like me, you can still lose a fish to jumping. I lost my scotts fairy wrasse when i was cleaning the tank and only had the lid off for a couple of minutes!
How about telling us about your tank and stock, we would love to hear all about it