Water Wolves of Water Gardens – Mink

Published on May 18, 2007


When the ice thaws off our midwestern water gardens, it is simply a wonderful time of the year. Things are warming up and everything starts to grow again. How did our Koi and goldfish survive the winter? If we had done a proper job of leaf cleanup in the fall and maintained some circulation in the pond to keep a hole open, then our fish should be fine.

Wow, it is discovered that all of your fish that you’ve had for many years are gone! Not even any fish carcasses are found! What possibly could have happened? The raccoons that raided our bird feeders last fall and winter must have eaten them. What else could it be because we have not seen any other kind of critter around?

More than likely the animal responsible was a mink. They can slip in and out through the ice layer by way of the hole that is maintained. They can do this silently, take a fish, and then slip out without leaving any obvious evidence that it was there. At one time, there may have been a few scales or some mink tracks left behind but if you do not suspect a problem, why would you look for evidence?

These water wolves of our water gardens can be devastating for our clients especially the ones that view their fish as part of the “family.” It is amazing how often I have seen the evidence of mink predation and the client thinking that their fish are just hiding. These little critters are silent killers leaving very little evidence so it is tough to know they have a problem until it is too late to do anything.

Aqua UV
Almost without fail, most water gardeners do not know that mink are present in their area. This combined with the fact that they are nocturnal, that is, being active primarily at night – they will not be seen or even suspected. Occasionally, mink may be active with some daylight but it is still difficult to detect them because they are small and move swiftly.

They can kill and eat the largest of our fish as well as the smallest. They are very efficient swimmers that can stay underwater for several minutes – even cold water. When it is cold, mink are the most efficient killers because the fish are lethargic due to the lower water temperatures. Whereas the mink are warm-blooded and can swim relatively fast to catch a fish. During the summer, it is a different story. The exact opposite is true and most fish can escape their jaws especially when “structure” is added to the pond.


The best structure is of the type that the fish can hide in, behind or under. A good example is black plastic storage crates that also serve a dual purpose to hold plant pots up off the bottom. Larger fish may need something else like plastic barrels that have been cut in half or have large enough holes cut in them so the fish can swim in and out easily. Structure may also be created with rockwork or underwater caves can be purchased (ex. Koi Kastles). The point is to provide something that the fish can escape from the mink’s teeth.

Mink occur over almost the entire United States and Canada with the exception of the desert southwest and tundra areas. A mink’s basic habitat requirement is a suitable permanent water area. So, water gardens that are within a mile or two of naturally occurring water, like a creek or lake, are more susceptible to having mink predation. However, there are instances where a wandering mink will find a pond further away. If a creek is within a stone’s throw of a client’s water garden and not in the desert southwest there is a very good chance that a mink will show up sooner or later.


There are a few things to look for to determine if a mink is preying on a water garden’s fish. If the fish are large that are being eaten, then scales will be evident. The mink has to drag the fish out of the water to eat it and in this process, scales will be left behind. There may be some fish parts left over but do not count on this. Mink track may be in the snow or mud. It is possible that their wet footprints will be left behind in the morning on the rocks or some hard surface but check for these in early morning before the tracks evaporate. Remember, nothing else will be disturbed around the pond. A raccoon will leave all kinds of disturbance, in most situations, especially if all the fish have been taken. One last thing to look for is how easily the fish are spooked. If they seem agitated then there is a good chance that a predator has been after them.

To stop mink predation you have to react immediately otherwise by the time you have rounded up the necessary tools to deter mink it may be too late for the rest of the fish. So, I always recommend to dye the water black the DAY you suspect a mink problem. This means either the pond owner needs to have some dye on hand or you need to have it on hand for your clients. For pond owners that I feel are vulnerable to mink, or even some other predator, I always advise them to stock the stuff. If they depend on me having the dye and they cannot get in touch with me immediately could spell certain death for more fish the next night. Once mink find a good source of food, they will be back in successive nights until the food source is gone.

I like to use black because it is the darkest. If the mink cannot see their prey then the fish are safe. Dyes made for water gardens will dissipate in time and do absolutely no harm to the ecosystem.


There are not very many good easy solutions for the pond owner that has had a mink show up. After the water is dyed then the next choices are to keep a large dog that has free run of the water garden area 24 hours a day. Keeping inexpensive fish is an option for the future but that is not really a choice at this point. If the pond is covered with ice, except for the circulation hole, then cover it with 1/2 to 1 inch hardware cloth or welded wire. Another alternative is to use a 12 inch high electric mesh fence for a month or so.

The best solution, in my view, is to remove the critter that is eating the fish. Trapping may not be what you can do or would prefer not to do but it WILL work. Contact the local DNR to make sure that you can legally do this. A pest control person/trapper may be able to help if you do not have the expertise.

Of all the critters that can prey on fish in our ponds, mink are the most difficult to detect and to deter. Knowing that they are around and that they can be a predator is the first step in solving the problem. If there is the possibility of having a water wolf problem, make sure that you have black dye on hand. Then, detecting the presence of a mink and permanently solving the problem, is difficult, but can be done.

Kloubec Koi Farm

12 thoughts on “Water Wolves of Water Gardens – Mink”

  1. Mystery solved! We have restocked our Koi pond three time this past summer. No evidence was left when the fish disappeared. Yesterday, after a heavy rain, I came upon 4 mink (?) frolicking in the water on top of the net. Three of them scooted but the fourth hung back, making sure there were no fish. We are so frustrated and do not know what to do next. We have a humane trap but after 3 months only a possum has entered. Any suggestions?

    1. I happened to hear loud chattering one day and found my cat watching 3 baby mink at the pond. They were adorable, but later that day I looked out and saw the mother swimming in a tight circle, seemingly pulling my fish in around her. I yelled and she took off. In just a few days I have lost about 80 of my100 goldfish; many of which I’ve had for 7 or 8 years,so I’m pretty upset.

      I read this site and cut into sections about 6-inch diameter pvc pipe and placed them in the pond, but have yet to see the fish enter them. I also placed a few pans with mothballs around the pond. I haven’t lost any fish since then, so I hope the mothballs are working. I placed some rocks on the pvc pipe to keep it submerged, and none of that has been disturbed, so I’m thinking no mink have gone into the pond, although at times the fish are agitated at times when go out to feed them. Try the mothballs; I think it’s working. Even when it rains on them they still smell. I would be interested to know how you make out.

  2. Avatar photo

    From the Author, Jamie Beyer:
    What you have is a family of mink (an adult female with her young) that adopted your pond as their feed bucket. You have been so kind to keep the bucket well stocked with fish. Now the mink are expecting more fish to show up. They will check it out very frequently for many months to see if any show up. You have four options – one is to not stock any fish in the pond. Second, dye the water black so the mink cannot see the fish. You will still be able to see the fish when they come up to eat the fish food. (dying the water is easy and cheap — the dye is biodegradable and ecofriendly). A lot of public gardens dye the water black to give their plants the wow factor.

    Third option is to have a professional trapper take care of the mink. Mink are a tough critter to trap and to have a bunch of them is even tougher to get rid of ALL of them. The babies have been show your feed bucket and they will be as much of a problem as the adult female. One problem with this technique is that more mink will show up in time so you will need an active trapping program all the time.

    Fourth option is to cage your fish in the pond. Normally, caging fish is only done when the water is cool or cold. This is when the mink are the most efficient at catching your fish. The fish metabolism is slower due to the cold water and cannot swim as fast but the mink is warm blooded and can still swim fast. However, with your pond, the mink are really checking it out and can corner the fish since several of them are hunting at the same time. So the cage would need to be in your pond 12 months — at least for awhile.

    I like the dying option if it were my pond. Cheap and easy. The problem will be taken care of immediately. Make sure to make it dark.

  3. I first had a mink come and ravage my koi pond about 2 years ago. I managed to get the remaining fish out before it ate them all, but I lost about half of them. The mink was not afraid of us at all, it came by around 10.00 am in the morning when we were netting the fish out, and it walked up to within about 10 feet of us and just stood and looked at us. Eventually, I removed all of my fish and I set up one of the pre-formed ponds inside my basement and they are living in there now. 2 years on, and I still see the mink – I even saw it swimming in the pond in the middle of the day during the summer. So I think once they find a pond with fish, they keep coming back and checking over and over.
    This is in MA.

  4. Was wondering what has been taken my large 25 lb Koi out of pond & leaving them on my lawn. I live a block from Puget Sounds in Wa state which I guess otters and mink live. But because of the size & weight I thought a owl tried to carry them but dropped them. There is no indication of damage to the Koi except the tail being torn up. It happens at night so unfortunately it’s to late to save them the next day. I had 7 now only 5, we’ve had them 18 yrs so it’s sad to watch this happen. So my question; can this be the characteristics of mink to just drop them & leave them? Or, do anyone have any other ideas on what could take my Koi?

    1. Avatar photo

      From Jamie Beyer:
      re[y to Word Press question
      Jamie Beyer
      Sun 2/10, 10:25 PM
      llgelles pondtrademag.com
      Hi Patricia

      You do have the potential for Sea Otters which I have no experience with. However, for that kind of predator that lives in the ocean to be very far from the ocean, I believe, would be unusual. Also I am sure that big of a predator would have eaten a lot of the Koi. I truly believe that if it was a Sea Otter you would not have seen any evidence of your dead Koi.

      The best way to determine if it is a mink is to look for tracks on the rocks around the pond in early morning before they evaporate. That has been my best go to technique but it has to be right at sunrise. You can set-up a trail camera to capture them in the act at night.

      The tail being torn indicates a mink. In the process of trying to catch the Koi they tear the caudal fin. I am somewhat surprised that none of the Koi were eaten. Could they have dined on one that you could not find? They are known for killing more prey than they can eat. It is amazing how these small predators can drag out that size of fish.

      If an owl had taken them they you would see puncture wounds on the fish where the talons impaled it. The torn tail is the indication of a predator that pursued them in the water.

      Not a lot of options, like my article mentions other than to trap the mink. Good luck. Jamie

  5. Now I know where all my blue gills, bass, ducks & cat fish went! We have a mink and turtles in our pond. Our duck died a few years back.
    Putting up a good fight and even killed one of the minks protecting the other duck, so they both died! Next time I see that devilish thing I’ll get my gun and shoot it lol!

  6. I live in the Appalachian mountains of North Carolina and have a pond approximately 1/3 acre. It is 15 feet deep at it’s deepest end and the pond exists primarily for the purpose of raising trout, however, for reasons I won’t go in to, it is also FULL of common goldfish. I am guessing ten’s of thousands. I have seen the usual avian preditors, kingfishers, ospreys and herons, but I have just seen a mink. After reading your website and postings, I asked myself could a mink really clean out this many fish? There is possibly a thousand trout in the pond that I have to stock to the tune of about a dollar each. I love the wildlife and don’t mind a limited level of contribution to their lives, however, it would be extremely disappointing to find a mink has emptied my pond of all of my trout. The goldfish they can have. Could this be possible?

  7. Hi George

    Good question!!

    One aspect of mink predation is that when the water is cold during winter months is when most of our fish are vulnerable to this predator. The reason is that our warm water fish metabolism is so much less in cold water and they can barely “flick a fin” as I like to say. The cold water does not affect the mink’s metabolism and they are still very good swimmers even during periods of cold. Mink are also a threat when the water is warmer but not as much due to the fishes ability to swim faster.

    However, since trout are a cold water fish they are very fast swimmers in cold water and can avoid mink predation better. I cannot imagine mink taking out large numbers of your trout especially when the brightly colored goldfish are like neon signs and will attract the mink’s attention better. Trout are naturally camouflaged and more difficult for a mink to see.

    If it were my pond I would consider adding structure to your pond so that the trout can hide under/between obstacles that the mink would have a harder time negotiating. I guarantee that this would help reduce mink predation.

    This is my opinion but have not had direct experience with your situation. Remember mink make excellent very warm coats.

    Good luck Jamie

  8. Patricia Walsh

    I have lost quite a number of large and small koi to mink, in the winter.

    I have a sheltered area for them to hide and have dyed the water but due to an underwater spring the dye dissipates.

    Is there a type of underwater cage I could use that would keep the koi safe?

  9. Yes, there are large cages that will fit into large ponds for large Koi. The ones I have seen are home built and the netting/cage material needs to be small enough that a mink will not be able to enter. Your Koi are placed in the cage and that is their home. Unfortunately, they are normally not very aesthetically pleasing. For small Koi and goldfish of say under 8 inches or so there is the storage crate that is pictured. I only wish I could be more positive about dealing with mink predation. They can be devastating. Good luck. Jamie

  10. I have had Mink get in to my Chicken hutch and kill them so I covered the whole house in 13 mm stainless chicken mesh and so far the new Chickens have been safe

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