Pretty much every tank has them, and unless you have them in "plague proportions", or simply don't like them, they're harmless members of your CUC.
However, if you're inundated, it means there's too much food for them in your tank, so the first thing to do is cut back on feeding the tank.
An easy way to catch them is to take some meaty food and pop it into the toe of an old "nylon" stocking. Tie it shut, and drop the packet into the tank on a string at lights out. Give the BW's an hour or two to find it and haul the stocking and the BW's out by the string (their spines stick to the stocking). Repeat as needed.
HTH