i put a small blackfish and a cunner in my 180 a few years ago -- just tossed them in and they did fine for a few months -- when i got sick of them i caught them both with sand worms (grinded down the barb on a hook) and pulled them out --- it was actually pretty cool to see them dart out of the rocks, take the bait, and quickly retreat back into the rocks ---- as they do so will in their natural environments
not a good addition to the tank thought, they continuously made a huge mess of everything.