Q. The pond I built last summer is located in a marshy area in the woods behind my house. It is 8 feet wide, 6 feet long and 2 feet deep in the deepest area. There are rocks along the bank to walk on. This spring natural plants, such as skunk cabbage, began to appear.
I stocked the pond with three 5-inch goldfish, 13 2-inch goldfish and one 5-inch koi. I also stocked a few small bullfrogs and leopard frogs that I caught in a nearby stream. The fish are doing well, but there are a few things that concern me.
One is the great blue heron that comes by once in awhile. Because the goldfish are so easily seen, how can I keep the heron away? Also, is there a chance the goldfish will breed? Finally, is a diet of white bread good for my fish? I would buy food in the pet stores, but it is very expensive.
A. It sounds like you have a really interesting pond. You are right about the goldfish being easy pickings for the heron. There is really no reliable way to keep the heron away other than putting a net over the pond. Great blues fish during daylight hours, so a net might do the trick. If you had dug the pond to a depth of 3 or 4 feet, with steep sides, the heron would probably just stand on the bank and stare, but would be frustrated in its effort to catch fish.
Try landscaping around the pond bank to make it more difficult for the heron to approach the pond edge. A good 3-foot fence will do, although it may not look so great. Many devices are sold to scare herons — water cannons, barking dog tapes and so on, but none really works well over the long run. (One possible solution is to push stakes into the ground around the pond, leaving about 6 inches of stake above the ground. Use monofilament fishing line to connect all the stakes. The herons apparently won’t step over the line. — Ed.)
You can be quite sure that the goldfish will breed, and in this context I should point out that your pond will quickly become overpopulated. Perhaps the heron is doing you a favor by keeping your goldfish population in check. Of course, the heron will almost certainly catch the most colorful and fancy of your goldfish first, largely because fancy goldfish swim the slowest and are easiest to catch.
A diet of bread and water is even more unhealthy for fish than it is for humans. Healthy goldfish need a variety of vitamins, minerals, oils, fats, proteins and other things that white bread — or any bread for that matter — do not contain. If you want to raise ornamental goldfish, one of the accepted costs is quality food. You do not have to use the premium brand fish foods. There are many good pond fish foods available at very reasonable prices. A good pelleted catfish food, for example, will also work fine.
Finally, by now you have probably discovered that the frogs you transplanted have wandered off. It does little good to bring them to the pond because they will just leave. Wait a season or two and frogs will show up on their own — and stay. By the way, you do not want bullfrogs — they will eat your fish, too!