This is a cool idea:
https://forums.saltwaterfish.com/t/358007/to-catch-a-pseudochromis
The fishing hook approach also can work well. You can also try always putting a net in the tank when you feed. eventually they will get used to it, but you still have to be very very good to catch them.
There are some fish traps that are easy to make as well (like above). Most will require some amount of "getting used to it" so that the fish is not suspicious. Food is then put in there as bait and the fish can not escape. However, it obviously has a big risk of catching any of your fish.