Steve Hopkins

December, 2011

There are many predators that like goldfish as much as we do.  Goldfish are brightly colored and contrast with their surroundings.  They are not as athletic as their carp ancestors and, thus, are easy to catch.  They are kept in shallow containers where it is difficult or impossible for them to escape and hide.  They are kept in groups so if you find one there will be others.  It is not surprising that predator problems and predator control often becomes an important aspect of keeping goldfish outdoors. 

When dealing with predators, we must remember that our nemesis is just trying to make a living like every other creature.  It is their job to feed themselves and their families in the most efficient way possible.  They would be remiss in their duties if they did not take advantage of an easy meal.  The predator will be, or will quickly become, aware of the goldfish keeper and the keepers claim of ownership.  Such conflicts between species (us and them) are common in the natural world.  It is not a matter of right versus wrong or good versus evil, it’s just life in the wild.

Over the years I have had conflicts of interest with a variety of goldfish predators including raccoon, otter, mink, housecat, belted kingfisher, cormorant, anhinga, great egret, snowy egret, great blue heron, little blue heron, green heron, black-crown night heron, yellow crown night heron, brown water snake, water moccasin, American alligator, bull frog, leopard frog, red-ear slider, red swamp crawfish, green darner dragonfly, predacious diving beetle, and probably others which are now forgotten.  This is just my personal list and reflects areas where I have lived.  Your list will be different.

Note that many of these are protected or regulated species.  There are stiff penalties for killing, harassing, handling or transporting some of these predators.  As goldfish keepers we must know the law, be sympathetic to the plight of wild animals in general, respect the values and convictions of our neighbors and not do anything stupid.  As a general rule, the focus should be on excluding predators, not eradicating them.

It can be seen that goldfish predators can be grouped into the mammals, birds, reptiles/amphibians and arthropods.  Some walk, some fly, some creep, some slither and some burrow.  When goldfish are kept out of doors, excluding all types of predators can be a challenge.  The only thing that approaches a fool-proof option is to keep the fish inside; and sometimes the housecat or an open window thwarts even that.

Exclusion options can be roughly divided into physical removal, scare tactics and barriers.  Physical removal is seldom an option when the predator is a mammal or bird.  The offending individual can come and go at will, will be difficult to catch in the act, and may be a protected species.  Sometimes a reptile or amphibian will take up residence in a pond and can be captured for physical removal.  We do not usually think of a snake or a frog as having much of a memory or sense of direction, but they will fool you.  When relocating them you should take them as far away as seems necessary, then double the distance.  Think in terms of miles, not yards.

When a mammal or bird predator problem arises, most people will first turn to scare tactics as they are easier, and less costly to implement.  Scare tactics work best if implemented before a predator has developed a taste for goldfish.  The perceived risk for the predator must be much more intense if the rewards are already known.  Scare tactics include the family watch dog, scarecrows, motion sensors hooked up to a water sprinkler (also called a Scarecrow), shiny pie pans, CD’s and streamers suspended from trees, evil-eye balloons and all the rest.  They all work…. for a time.  A predator may be scared away and never return if food is plentiful and the other options have less perceived risk.  But, when the other options require a lot more work than a meal of plump goldfish, the predator may study the situation and assess the real danger of streamers, other distractions and a dozing dog.  Once the predator has snatched a fish and become habituated to the scare tactics their effectiveness will be lost.  I have found that most birds and small mammals are smarter than my dog and smarter than me.

When scare tactics no longer work, more effective barriers must be installed.  Like scare tactics, barriers work best when installed before the predator has developed a taste for goldfish.  If I only knew then what I know now, life would be much easier.  Barriers include fencing, lines stretched across a pond, netting, and the like.  Fencing is not of much use for preventing entry of most predators.  They will either go through it, over it or under it.  Some suggest using monofilament line stretched over to pond to prevent entry by birds.  This may work for a time, but most birds will learn to walk in rather than fly in so they can slip between the strands of line.  Netting has its drawbacks too, but comes closer to being a long-term solution.

Once a fish keeper has decided to resort to netting, the first approach is often to stretch plastic net over the tub or pond and secure it with stakes or a few cross members.  When the netting sags into the water it can occasionally trap the fish it is designed to protect.   Herons are not reluctant to walk on netting, forcing it into the water and, perhaps, giving them access to the fish.  I have watched a night heron peck at a spot in plastic netting until a few strands are broken and the bird can squeeze through.  Raccoons, mink and other small mammals will readily chew through plastic netting.  If the mesh is small enough, plastic netting works fairly well for excluding frogs and can be a death trap for water snakes.  The snakes will try to squeeze through the netting and become trapped; unable to move either forward or backward.  So, before putting up netting remember that it must be supported well above the water surface and you may need to use metal rather than plastic, especially where small mammals are involved.  Poultry netting (chicken wire) is pretty effective, but may be difficult to work with.  Some persistent raccoons and mink may tear through poultry netting and require welded wire to exclude them.

You will soon find that working with and enjoying your fish is more difficult when the tub or pond must be kept covered with net or wire.  Taking off the netting to dip out a few leaves can be a constant inconvenience.  I have numerous small ponds and tubs.  After several iterations I have found it most convenient to build large net enclosures over groups of ponds.  The enclosures are eight to ten feet high and complete with doors.  Around the perimeter of the enclosure is a two-foot high “fence” of one-inch poultry mesh to exclude frogs, turtles and the mongoose.  Above the chicken wire is 1-1/2 inch plastic netting to keep the herons and dragon fly out.  A few wooden posts and eighth-inch line create a framework to support the netting.  Our local herons only peck holes in the netting at ground level so this approach has worked out fairly well with our particular suite of predators here in Hawaii.  The situation and response will be different in your area.   

All of the various types of retrofitted barriers have one thing in common… they are ugly to look at.  The smart fish keeper would include predator control in the original design of the pond and surrounding landscape.  This forethought has several advantages.  By having the predator barrier in place before the fish are added, the predators will never develop a taste for goldfish and, thus, will be less aggressive about trying to break in.  Secondly, by thinking about predator control in the original design you will be able to find a visually attractive solution and, perhaps, a predator barrier which serves several purposes.

Do an Internet search for lath houses.  A lath house is a structure with widely spaced pieces of thin wood.  They were used to provide partial shade for tender plants in the days before shade cloth.  Designs range from simple to ornate structures with Victorian era influences.  Some sort of lath house-like structure can protect your fish from most predators, provide partial shade for the fish if needed, provide a trellis for climbing flowering vines, and the weathered wood just looks better than wire.  When we lived in the Southeast, we had a lath house that served triple duty.  It provided predator control for a fish pond, provided shade for the pond and some potted plants during the heat of summer, and then it was covered with plastic sheeting and converted to a hot house to provide warmth during the winter.

If you are contemplating a goldfish pond or outdoor tub, it will be worthwhile to talk to other enthusiasts in your area through a club or social media about potential predator problems.  Just because you have never seen a heron or raccoon in your courtyard does not mean you never will.  Goldfish can be a magnet for both people and predators.