Here's how I caught mine. If you have enough space on one side of your tank to fit a divider then you could do the same. I bought a piece of thin flexible plastic/acrylic (cut to the size that will fit your tank) from a plastic store and some divider clips (), I divide a small area in one side of my tank with the divider and left a small opening at the bottom of the tank so the fishes can swim between the two areas, I placed a piece of nori on a nori clip on the small side of the divided area, and once the fish swims over to the nori side I would push down the divider to trap the fish, then it makes it easier to catch the fish in a smaller area of your tank without touching any of your rock work. Hope this helps. Goodluck!