The fish net works well. You can also build a trap by taking a two liter pop bottle, cut the neck off, invert it, reattach it, drop food in, and sink in the tank. Eventually the shrimp will smell the food and crawl right in.
finally caught the shrimp. Tried everything that was suggested and he wouldn't cooperate. My husband chased him with a turkey baster to the top and grabbed him with his hand. Now he is in another tank, by himself.