My fish are just plain DUMB!

[lastlight]

have someone hold a small mirror up above the overflow to see down there while you work too.

[sphelps]

Usually I find the easiest thing to do is remove the standpipe and flush the guy into the sump. Have a net waiting in the sump around the overflow pipe.

[MMAX]

I had the same problems with my orange spot goby and more recently my lawnmower blenny (always thought he was too fat to fit through the egg crate but he suprised me). I shut down my return pump and opened the gate valve to drain most of the water out of my overflow. Raised my lights, stood on a chair and leaning over the tank used 2 nets to trap the little bastards. I kept one net stationary and used the other to chase them in. I got pretty good at it because they didn't learn their lessons after the first time.