You will have a fun time trying to get them out, I had to do the same thing a few months ago. Try putting some brine shrimp or other fish 'treat' in the tank and have the net in the tank, when the fish comes tward the food scoop up. This worked for me, took a few times though. Good Luck
I net them at feeding time too. It's the only time I overfeed my fish. It's a case of giving them enough to keep their interest. If you put a whole cube of frozen brine shrimp in then they stay in one spot and don't dart everywhere. Not tried this for marine but it works for freshwater...
Or try a Trap-Eeze. This worked for me getting some yo-yo loaches who dug themselves in well in a FW tank. Without the trap-eeze I would have had to strip out all of the rocks and plants to get them.
I've never had any probs catching my fish, longest was probably 2 mins at the very most trying to catch one, guess ya just gotta think like a fish and outsmart it. I have pretty fast reflexes too though which helps a bit I guess
Trap-eze is a fish trap - works like a charm. You put food in a compartment at the back of the trap and have a string attached to a release. When the fish you want goes after the food pull the string to trap the fish and you can then lift the entire trap, including water, out of the tank. I've used one with great success in freshwater tanks.
Using a tazer is cruel and unneccessary! I find that if you use a mains-powered electrical appliance, switch it on and drop it into the water, then the resulting lack of house lights also reduces the stress on the fish.