Catching most marine fish in a tank is almost always a painstaking and time consuming process. When moving limerick around is not an option, which I assume is the case for you, relentless attempts to catch them with a net often takes a very long time and can stress out other fish in the tank. As a first step, I would recommend placing a net 3-4 inches bellow the water level facing upwards and leaving it there for an hour or two. After it has been in the tank like this for awhile without having been moved, try adding a little bit of food to the tank right above the net and prepare for swiftly moving the net up once the desired fish are above it. If this does not work, temporarily adjusting water flow to direct it into areas where the fish prefer to seek refuge can make the fish easier targets to catch. Doing this while also using multiple nets to corner the fish is often helpful as well. If none of these methods work for you or are not possible with your setup, let me know!
