Muskrats are a preferred forage item for Mink, which is the reason I like them around. Further, they are amazingly cool critters - and although rare to see them, I like knowing they're around patrolling for Skrats.
I had a mink clean out cages of fish I wintered over - but even that didn't change my feelings towards them. I have learned the importance of tying my cage lids down over the winter months, however.
I have seen no evidence that mink are impacting my fishery to any degree over the past 9 years - only one fish which appeared to be mink casualty was a smallish SMB with everything eaten but the head about 6 years ago.
Otters, pelicans, cormorants are a different story, but Mink are welcome in my pond.