American Mink

Mustela vision, or the American Mink is mysterious to most.  They are usually dark brown with white patches on the chin, chest and throat.  Their bodies are slender with short legs and a pointy flat face.  They are mostly nocturnal and semi-aquatic equipped with webbed toes.  Their semi-aquatic nature is why we as pond and water garden owners need to be on the look out for the mink. 
Mink are found throughout North America except in the Southwest.  They are bred on farms or mink ranches to support the clothing industry and alleviate pressures on the natural population.  In the wild, their ideal territory is along a stream, pond or lake with some sort of bushy or rocky cover nearby. 
Mink can be harmful to pond fish in ponds and lakes and koi fish in water gardens and koi ponds.

American mink

Winter melts that quickly raise the water levels of streams will displace mink from their dens and that is when you are likely to see signs of a mink in your pond or water garden.  Periods of drought that dry up their fishing holes will also cause mink to be on the move. 
Mink are fearless and voracious predators that will stay and defend itself from animals much larger than they are.  Mink are carnivores that can take down an animal twice it’s size.  We have seen a mink take a butterfly koi over twice its size out of a large koi pond!  The diet of the mink consists of any meat they can get their paws on including crayfish, frogs, fish, small mammals, birds, ducks and other water foul.  Mink will not eat water plants or control algae. 
Mink can decimate your fish population regardless of whether you have a large pond or a water garden pond.  A mink can swim underwater for 100 feet without coming up for air!  During winter look for small animal tracks that lead to and from a hole in the ice of your pond.  Mink usually carry and stash their prey to a protected spot like under a deck, shed or bushy covering nearby.  Look for signs of a fight like small drops of blood or fish scales. 
If you think you have a mink problem there are professional trappers in the phone book that can give you a hand relocating these terrifyingly adorable creatures.