I would think along the same lines of gallop, with a twist.

I would pump the pond down, since the size is smaller. If you start seeing fish of sizes that should be there, fill it back up. If no fish, pump down more and start over.

Still seems odd that they are all gone. Makes you wonder what may be wrong that it will happen again.

Edit- or hire a pro for a fish survey.

Last edited by fish n chips; 04/15/13 07:46 AM.