Awhile ago when I had two damsels that I wanted to remove, I had a large net. I put opened the top of the aquarium,and just put some food in. I waited till they came up and I had to be really quick. I got one, but the other was still in there. What I did was had another person get a net and cover the damsels favorite place to hide, and kind of "shoo" him towards my net.