MISSING - Presumed IDIOT!!!

After retuning from the pub i go to check on the little guys. After a scan around i notice we are one fish short!!! A bit shocked i search frantically about looking for little Cousteau. Worried he might have been eaten by Jacques, highly doubt it though. I opened the lid to see Cousteau behind the back wall on the right trapped in the filter section of the tank.

God knows how he got in there, let alone how to get him out!