One of the biggest challenges with a garden fish pond is keeping fish safe from predators. If you aren’t careful, you can spend a considerable amount of money replacing fish that vanish on a regular basis. There is no guarantee that you won’t ever lose fish to predators, but a little planning should help keep them safe.
Found in increasing numbers in gardens in the US, UK, and elsewhere, where they nest in trees and bushes, the great blue heron (Ardea Herodias) is the most common predator of pond fish. The great blue tends to be 3 to 4.5 ft. in length with a wingspan of 5.5 to 6.5 ft.
They are a wading bird that feeds alone at dusk and dawn eating mostly small fish. There are several other diving birds that are a constant nuisance to fish in garden ponds; the kingfisher and eagle among them.
A fence around your pond can be a good deterrent against herons, though it is not the most attractive thing to look at. Herons will land beside a pond then either lurk at the side or step into shallow water. A fence can prevent this very effectively.
The raccoon (Procyon lotor) is found throughout North America with its natural habitat being sparsely wooded areas. Raccoons are very smart and adaptable, so they have easily found their way into urban as well as suburban areas. Raccoons are nocturnal and their preferred foods are fish and frogs.
Other predators of a garden fish pond that can be difficult to control are cats, snakes and frogs. Who doesn’t have one or more of these in their neighborhood or backyard?
Before building a pond, there are things to consider that will help deter predators.
Fish protect themselves if they have places to go when threatened. Building your pond at least 3-4 ft. deep makes fish less visible to predators, allows them to dive when threatened and keeps them out of the reach of shallow water hunters.
Also, ensure that there are caves and tunnels for fish to hide in when predators are about; even adding one or two rocks will provide protection for exposed fish.
Finally, pond foliage such as lily pads, hyacinth and other pond plants give fish places to hide.
Consider the types of pond fish you plan on using in the pond. Koi fish for garden ponds are not a good idea if you are going to add plants. Koi eat plants and you will be constantly replacing them.
Comet goldfish, shubunkin and rainbow dace will not eat your plants, and are an excellent choice of fish for garden ponds because they are smaller and faster swimmers than koi. Rainbow dace have an added advantage in that they will eat mosquitoes.
Other types of pond fish to think twice about adding are ryukins, orandas, celestials and any moor fish—they are all slow swimmers. Sara fan are also vulnerable because their double fan tails make them more visible and slower to move.
Decorative Additions and Aggressive Tactics
Decoys are decorative and excellent deterrents. A territorial bird, herons will be deterred by another heron decoy. Move it from time to time, though, blue herons are bright and eventually will ignore the decoy if it is static.
Other decoys include a floating alligator and the Garden Defense Electronic Owl. The owl is motion sensitive and will move and screech when a predator of any kind approaches.
The scarecrow sprinkler system is similar in that it is motion sensitive, but it shoots a stream of water at any predator that comes around.
Other devices include ultrasonic sound makers that send out noises that only wildlife can hear. Finally, consider getting a dog. A dog is one of the best natural deterrents to predators, provided your dog will stay out of the pond himself.