You can build a trap out of a critter keeper - the plastic container w/the swining lid. Use fishing line & set it up like a trap door, so that when the fish go inside, you can pull the line & the door will close. Don't feed the fish for a couple days. Then put the food inside the trap. It may take a few days, but they'll eventually go in. Especially if they're aggressive.
Picture a box w/a stick to hold the door open. The line is attached to the door & strung through the lid. The critter keepers have vents, string the line through those. When you pull, the door shuts & you can pull the box right out w/the fish in it. Hope this makes sense. It's hard to describe.
Juli