Fish bullying
 

The offender is a damsel with seniority and a real bad attitude
The victim black cap basslett
How can I get the damsel out without taking down the the aquascape?

try feeding with a net until the fish swims into the net to get some food. It took me about 4 days to get all my fish to swim completely into a net to feed. Except the stupid clown I was trying to catch, but that's another story.

Is there any way of clearing a small area at one end of the tank,just enough to slide a piece of plexi down?Then you nudge the offender to the clear area and slide the plexi down trapping the fish at the end of the tank.This way your not chasing him all around the tank,less stress on everyone.

To much risk of damagin coral with the plexi but I will try raffs Idea .
I thought there might be traps of some sort available.

The best trap is a critter keeper. You can rig the door. And most food hungry fish will go in very soon. Give them a few days of safe eating in there and BOOM ... :mrgreen:

In the past I've been able to catch un-shy eaters (clownfish, chromis) in a large mouth jar. Similar to the net trick- just feed them with the jar already in the water to get them used to it, and then once they are near the mouth of jar put it below the surface and they should get sucked right in. Saves putting them in the net too.

I've had good luck with waiting till night and catching them while they're sleeping.Just wait a few hours after dark until they are sound asleep,get your net ready then flick on the lights,little fish is 1/2 blinded and slugish from sleeping,then just scoop him up.Some times you can heard him into the net if he is in a difficult spot.

I use a wide mouth jar trick as well but a different variation. I just set the jar on the bottom and wait for the more curious fish to swim in. If they aren't quite so adventurous you can bait the jar with food. Placing it near the damsel's territory will almost guarantee him checking it out. If he's too fast to lift the jar out with him inside then you can trap him with a net placed over the top / side of the jar. Patience is the key.