I had a yellowtail coris and it was definitely one of my favourite fish. GORGEOUS, very active and interactive all the time, amazing to see when it decides to dive bomb into the sand (yes, that means you need sand... at least 2 inches deep imo). only thing is that it does jump... mine did... about three days ago
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I had also heard that they can pick at soft corals when they are older so i threw a frag of zoos and a few shrooms in (it was a fowlr and my fish was an adult). It left my corals completely alone. I think the best way to do it is to find one for sale that is currently inhabiting a tank with coral (that's how i got mine). They aren't easy to catch once they're in the tank.
depending on the size of the 6 line, it might be okay. If the coris wrasse is a full grown 7 incher, then yeah any two inch fish might end up as food, but if you get a juvenile coris, then the 6 line should be completely safe.