Jose,

Here's a bit advice. When we were taking our 240 down we used egg crate the width of the tank and doubled it so the holes were not so big he could escape through.

We then rounded our wrasses all on one side of the tank and moved the crate towards the end of the tank to minimize the space they had to swim to a very minimal. We were able to catch them all in no time. And of course we used a net.

Hope this helps! It also works on catching your fish in a tank full of coral.