A couple months ago, I added a Red-headed Fairy Wrasse to the tank. My Mimic Tang bullied it for a bit, until it lost interest, but the wrasse spent quite a bit of time hiding and peaking out to see if the coast was clear. Then I went on vacation. I've had an issue with return flow, I had to turn it way down, but I was able to fix it when I got back, but I've noticed the wrasse is a completely different animal now. He has a severe case of the zoomies, swimming rapidly across the tank, up from the bottom to the top, back down, all over the place. It's pretty cool, as long as it's normal. I want to make sure this behavioral change is not symptomatic of something bad....