That is the only way to catch them (ba$tards). We moved the tank from West Palm Beach to Fort Myers over 1.5 years ago and had to try and catch 3 of them. These all died later because of a Hatian Anenome that the store sold to me after it was just delivered that week!
SO I bought him (bluefin) when he was half the size and another blue/yellow one(timid in my experience) to restart my tank.
I did not know he would be as aggressive as the Domino/Snowflake damsel but soon I will have to remove him or risk loosing the 6line. (I hate LFS that don't notify you of any possible probblems, I knew they could be men but he is REALLY mean)
I have seen him pin the poor wrasse at the surface and I can't deal with it anymore.
So sometime this week I will have to set up a temp tank for him or bag him and go to the fish store. Sadly they are a 30 min drive from me at my house and I work all week long. Hope I don't see any dead fish, I only added the wrasse because I was told that they were tough and wouldn't take anything from a damsel, well not mine. (To each their own)
Good luck let me know how the capture goes! I may need to make fish food out of him instead!
:cheer: