Almost every aquarist owns a catch net. But one isn’t enough! Having two different sized catch nets helps you to catch fish much more gently and more stress-free (for fish and aquarist). Use the small net to direct the fish into the large net and calmly lift them out of the water. Holding your hand underneath the net will make the fish wriggle less and reduce damage to their mucous membranes.
Find fine mesh catch nets in various sizes here: JBL Fish Net, fine
Find coarse mesh catch nets in various sizes here: JBL Fish Net, coarse
You can find further useful aquarium utensils in the Themeworld Aquarium: Useful equipment