Fish and invertebrates are not normally considered to be nuisance organisms in ponds except for a select few species. Considering that fish and invertebrates are some of the most species rich of all of the groups of animals, there is no way that this page can cover the biology and control of all of these animals. It must be noted, however, that most fish and invertebrates are either beneficial or benign to stormwater ponds or are not adapted to survive well in these artificial aquatic environments. That being said, there are a few fish and invertebrates that may become nuisances if released into a stormwater pond. Also, exotic animals pose a significant threat to native species and ecosystems. Because stormwater ponds discharge to rivers, wetlands, and other natural aquatic systems, exotic animals that are introduced to stormwater ponds are likely to spread and colonize other natural systems.
What fish are nuisances in stormwater ponds?
The most problematic fish in stormwater ponds is the Common Carp or Israeli Carp. The common carp (Cyprinus carpio) is sometimes mistakenly stocked in ponds to control aquatic weeds or as an ornamental fish. Unlike the sterile grass carp, these fish can reproduce quickly in small ponds and affect water quality and the health of other fishes. The most significant problem common carp cause is muddy water. They have a tendency to root in the bottom and stir bottom sediments as they bed and feed. This can be a problem for stormwater ponds whose purpose it is to trap sediments coming from the development. Muddy water may affect the health of other fish in the pond and may result in water quality impairments downstream. It is recommended that common carp be completely removed from stormwater ponds.
Other introduced fish may become problems as well. No aquarium animals should ever be released into stormwater ponds! Oscars, pacus, suckers, goldfish, koi, golden shiners, and many other fish have the potential to cause significant problems in ponds and receiving waters downstream. *Special note* Two fish have received special attention recently because of their potential to become invasive in South Carolina public waters. The northern snakehead and silver carp (a.k.a. Asian carp) are causing significant problems in other states but have not been introduced into South Carolina yet. Do not allow your stormwater pond to be their point of entry!
Stormwater ponds should be stocked with fish to help maintain biological services and the ecological balance of the pond. The only fish that should be stocked in stormwater ponds are bream (bluegill/redbreast), largemouth bass, triploid grass carp, and tilapia) See section on Fish Stocking and Harvesting.
How are nuisance fish controlled?
The only absolute control for common carp and other nuisance fish in stormwater ponds is to drain the pond and harvest the fish. Though this may seem drastic and aggressive, this will protect the ecological integrity of the pond in the long run. Other fishes (bream, bass, triploid grass carp) can be restocked and will rebound rapidly once the nuisance fish are removed.
What invertebrates cause problems in stormwater ponds?
Until recently there has been little concern over invasive invertebrates in stormwater ponds, that is until the Island Apple Snail was released into a stormwater pond near Myrtle Beach, SC where it quickly spread to neighboring ponds and into the Intracoastal Waterway. The island apple snail (Pomacea insularum) has the potential to decimate native plants, displace native snails and other molluscs, and has the potential to transfer meningitis. Its introduction has drawn attention to the threat of other freshwater invertebrates, which may be moved via the aquarium trade and mistakenly released into a pond by a well-meaning but misguided resident. Other freshwater invertebrates such as zebra mussels are not established in South Carolina yet, but have officials on the lookout.
How are invasive invertebrates controlled in stormwater ponds?
If you suspect that you have an invasive invertebrate such as island apple snails or zebra mussels, contact either your local wildlife office of the SC Department of Natural Resources or the SC DNR Aquatic Nuisance Species Program. They may be able to assist you with control.
Are there any nuisance insects to worry about?
Sort of but not with stormwater ponds. Residents are often concerned about mosquitoes and other insects that emerge from ponds. Stormwater ponds are not normally suitable breeding habitats for mosquitoes. The ponds are too deep, the water surface has too much motion, and there are too many predators (fish and other insects) for mosquitoes to effectively breed in ponds. The only time when ponds become suitable mosquito habitat is when they become overgrown with vegetation that covers the surface. The plants make small pockets suitable for development of mosquito larvae. Often residents will complain about a massive emergence of mosquito-like flies that do not bite, but they get into the house or cover the lights and siding. These insects are most likely the Midges (Chironomidae), which are small flies that look like mosquitoes with the naked eye but do not bite. Midges can thrive in stormwater ponds and often have mass emergences, especially in late spring and early summer. The good news is that they usually are short lived and do not cause any property damage or pose a health risk at all. If midges get into your house, it is best to control them with a vacuum cleaner with an extendable hose. Spraying insecticides in homes is not a recommended method to control flying insects indoors.
How can our community control mosquitoes?
The mosquitoes that are most problematic in neighborhoods with stormwater ponds are usually coming from other water sources than the ponds. Small containers such as clogged gutters, bird baths, drip trays under potted plants, buckets and toys that collect rain water are common breeding habitats for mosquitoes. A few species of mosquitoes reproduce in isolated pools in the marshes and forests. The best way for home owners to manage mosquitoes is to 1) reduce mosquito breeding sites by emptying containers that collect rain water and 2) protect themselves using repellents and long clothing. For more information on dealing with mosquitoes, consult your local mosquito control program or the Department of Health and Environmental Control.