They aren't an issue unless they get crazy, at one point I had about 100 in my 150. I had some that were eating zoa polyps on frags I had, they never went after the colonies but they would hit my frags pretty good. I got a single harlequin shrimp and he cleared them up in about 2 months. I still have a population of them in my sump so I pull 3 or 4 a day out and throw them in the display.
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