I used to like seeing amphipods in my filter socks.. thought they are good for the tank... Now, they are thriving and I have probably hundreds! some are huge! Pretty sure they have eaten a nice purple monster zoa colony, a huge nirvana zoa colony and big blasto colony! =/ They were all very healthy and started to fade for no reason. Confused till I flipped over the frag tile that the nirvanas were on! All different sizes of amphipods scurried away from under there! There must have been like 20+!
Took a flashlight to spot check at night, and they were chilling on the frag tiles. Not seeing them actively eating the zoa but 99% sure they ate them.
I used to intentionally leave gaps under the tiles so pods can thrive... HUGE mistake! Now I'm trying to make sure they have no place to hide but every time I pull a frag out of frag rack, there are a few that scurry away.
I used to have a red coris wrasse that always flipped my stuff over and driving me nuts! Now I know why. Had to sell him as he was getting big fast! Got a melanurus wrasse but it's not doing much. Had a pod flow right by her nose and no response.
I run bare bottom which really limits my choice of predators.
But yeah, while copepods are probably beneficial, amphipods must die!