The Permit Issue

After you have removed non-native, invasive species, the next step is to encourage natives to come to your pond. Because it is currently difficult to obtain a permit to keep native wildlife, your best bet is to setup a native plant pond, keep it native species friendly in anticipation of someday being granted that permit, and hope that, with invasive predators at bay, native wildlife will find a safe haven at your pond. Expect birds like warblers and Coopers hawks to frequent the pond. Dragonflies and damselflies will quickly settle in. Native frogs, toads and turtles have been known to find their way to backyard ponds. Species that arrive on their own do not require a State Wildlife Holding Permit.

Native plants can be acquired through local water garden clubs or ask your State Game and Fish department if they can put you in contact with someone who manages ponds with native plants. The plants need annual thinning so pond owners should be more than happy to share some of the excess.

As an alternative to fish for mosquito control, “Bti” (Bacillus thuringienis ssp. israelensis) are bacteria that infect and kill mosquito larvae. These bacteria are highly selective, killing only mosquitoes and their close relatives like gnats and black flies. Formulations of Bti will only kill these types of insects and do not harm other kinds of insects, fish, birds, worms or any mammals. Bti is available locally in hardware stores and ranch supply stores in a donut-shaped dunk or as granules. Once the pond becomes established with predatory aquatic insects, mosquitoes will have a hard time in the pond and Bti will be less necessary.

Even if you apply Bti, your neighbors may have concerns that your pond could be a mosquito hazard. For this reason, you may need to introduce nonnative fish that do not require a state permit or maybe you just want to have fish in your pond. Do not under any circumstance introduce “mosquito fish” (Gambusia affinis) into your pond because they might escape during a flood and harm native fish.

Goldfish are very good at eating mosquitoes, inexpensive, can be easily observed and are less likely to survive in the wild if flushed out of your pond. Goldfish are also a little easier to get rid of than other species. The tiny “feeder” goldfish you buy at the pet store can grow to 9 or 10 inches in a few years. The larger fish are less adept at catching mosquito larva and spend most of their time foraging for food in the muck on the bottom of the pond and can be a nuisance as they uproot your plants. The constant disturbance of the muck will cause frequent algae blooms better known as “pea soup”. It’s best to get rid of the large fish and try to maintain a population of smaller ones. 

Perhaps a safer alternative would be to use feeder guppies from your local pet store. Guppies will thrive in your pond all summer and are very effective at eating mosquitoes. The guppies will not survive cooler water temperatures so move a number of the fish to an indoor aquarium for the winter. In the spring as the pond warms, you can reintroduce the fish back into the pond if you desire.

Many exotic fish harbor diseases that could be harmful to native fish. Be sure to allow your pond to sit without fish for a season before introducing native fish to a pond that formerly supported exotics.