I am doing a water change on my 100 gal, and I found a left over feeder in the sump. It had even grown! It must have slipped in through the teeth in the over flow. So I tossed him in the main tank
I had a Magnum Canister filter once, and the intake filter fell off. At the time, I had about 15 clown loaches in there. When I woke up in the morning they were no where to be seen. Looked down at the filter to see all of them happily playing in the current inside the filter. Glad they missed the intake propellar!! Thats about the coolest I've ever experienced.