At the most basic level, aquatic invasive species are water-dwelling organisms that are not native to Minnesota. The impacts of aquatic invasive species vary. While some invasive species cause damage to ecosystems, others can cause human or economic harm.
Priority Species List
Every year at MAISRC, we review the aquatic invasive species that should be prioritized for research. We identify the invasive species that are currently in Minnesota, or are in areas immediately adjacent to Minnesota, and are likely to cause significant damage. A species may be considered as high-priority if there are key uncertainties that prevent researchers/managers from developing effective prevention or management/control programs.
Every other year, MAISRC systematically identifies research needs related to these high-priority aquatic invasive species in order to direct research efforts and investments to the state’s greatest needs. Learn more about our Research Needs Assessment process. View the Priority Species list as a PDF.
2026 Priority Species List:
Aquatic invasive plants
| Common name | Impacts | Click photo to learn more |
|---|---|---|
| Brittle naiad Najas minor | Brittle naiad forms dense surface mats that hinder recreational use, overtakes and outcompetes native aquatic plants | 
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| Curlyleaf pondweed Potamogeton crispus | Curlyleaf pondweed inhibits the growth of native species, interferes with recreational activities, and disrupts valuable services provided by native plants such as stabilizing sediment, improving water quality, and providing support for fish and other animals. | 
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Eurasian and hybrid watermilfoil Myriophyllum spicatum, M.spicatum x sibiricum | Eurasian and hybrid watermilfoil grow rapidly and tends to form a dense canopy on the water surface, which often interferes with recreation, inhibits water flow, and impedes navigation. Eurasian watermilfoil is a particularly problematic aquatic weed, due to its ability to reproduce from fragments and spread rapidly, its high growth rate in a range of temperatures and environmental conditions. Some genotypes of specifically hybrid watermilfoil are more tolerant of some herbicides and, thus, more difficult to control. | 
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Typha x glauca, T.angustifolia | Narrow leaf cattails can develop large monocultures, outcompete native vegetation and will crossbreed with native, broad-leaf cattails. | 
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European haplotype (common reed) Phragmites australis subsp. australis | European common reed is a tall, aggressive grass that can take over wetlands and shorelines, push out native vegetation, and reduce habitat quality for wildlife. The aggressive invader can also impact infrastructure such as roads, stormwater ponds, and agricultural ditches. | 
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Iris pseudacorus | Yellow iris is a perennial plant that grows in wet areas and along shorelines. It can form dense patches and crowd out native vegetation. | 
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| Purple loosestrife Lythrum salicaria | Purple loosestrife is a perennial herbaceous plant with bushy appearance. Populations can expand quickly and form dense stands that crowd out native vegetation. | 
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Nitellopsis obtusa | Starry stonewort grows in tall and dense colonies. It is known to form mats on the surface of the water that can interfere with recreation and potentially displace native plant species. | 
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Hydrilla verticillata | Hydrilla crowds out native species, impedes irrigation, and interferes with boating and recreation. | 
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Butomus umbellatus | Flowering rush creates dense growth along shoreland areas makes it difficult to access open water. It overtakes habitat and outcompetes native aquatic plants, potentially lowering diversity. It also provides unsuitable shelter, food, and nesting habitat for native animals. | 
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Nymphoides peltata | Yellow-floating heart develops monotypic dense patches that can exclude native plants and create stagnant, low-oxygen conditions in the water below. These areas of stagnant waters can be an ideal location for mosquitos to breed. If the population of yellow-floating heart is large enough, fish and other wildlife may be forced to relocate. The mat-like patches also impede recreational activities such as fishing, water skiing, swimming, and boating. | 
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Cabomba caroliniana | Cabomba is an extremely persistent and competitive plant that grows quickly and crowds out other vegetation. Cabomba forms dense mats that block sunlight penetration to lower water depths and shades out germinating seeds or propagules. | 
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Hydrocharis morsus-ranae | Free-floating growths of European frog-bit can lead to densely tangled mats, which can crowd and shade out native aquatic vegetation. It can dominate wetlands where it occurs, and the dense mats may effect wildlife as well as native plants. | 
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Invasive fish
| Species | Impacts | Click photo to learn more |
|---|---|---|
Cyprinus carpio | Common carp root in lake beds for food and in the process they uproot aquatic vegetation, increasing water turbidity and releasing large quantities of sediment-bound nutrients, which stimulate algal blooms. It is estimated that over 70% of lakes in southern Minnesota have lost their plant cover and suffer from excessive algal blooms due to carp’s foraging activity. | 
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Hypophthalmichthys nobilis; Hypophthalmichthys molitrix | Silver and bighead carp are filter-feeders, straining microscopic plants and animals out of the water and away from paddlefish, gizzard shad, and young gamefish which rely on them. This disruption affects native fish and waterfowl and could result in diminished recreational and commercial fishing opportunities in the region. Silver carp also pose a threat to human health due to their propensity to leap out of the water when disturbed by watercraft. | 
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Mylopharyngodon piceus | There is high potential that the black carp would negatively impact native aquatic communities by feeding on, and reducing, populations of native mussels and snails, many of which are considered endangered or threatened. | 
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Eastern mosquitofish, Western mosquitofish Gambusia holbrooki, Gambusia affinis | Mosquitofish are highly aggressive invaders that prey on and displace native species, disrupt food webs, and have caused documented declines and extirpations of native fishes and invertebrates, including threatened and endangered species. | 
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Ctenopharyngodon idella | Grass carp are voracious feeders that pose a threat to terrestrial plants, such as shrubs at the water line. Grass carp can also eradicate aquatic vegetation that serves as a food supply for waterfowl and as refuge from predators for young fishes. | 
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Gymnocephalus cernua | Ruffe grow rapidly, have high reproductive output, and adapt to a wide range of habitat types--because of these traits they pose a threat to native fishes. | 
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Neogobius melanostomus | Round goby impact the population of native fishes by preying on their eggs in large quantities. | 
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Carassius auratus/gibelio | Where released, goldfish can be responsible for the decline of native fish, invertebrate and plant populations in different areas. Furthermore, it is notorious for increasing water turbidity because of its habit of stirring up bottom sediments during feeding. | 
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Scardinius erythrophthalmus | The Rudd is a somewhat stocky, deep-bodied fish with a forked tail, and the mouth is distinct with a steeply angled protruding lower lip. The Common Rudd has omnivorous feeding habits that can change with temperature and season. Generally, their diet includes macrophytes, bryophytes, and filamentous algae along with fish and some other animal material and detritus. | 
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Channa argus | High potential for outcompeting native species for food resources and altering food-web dynamics due to its voracious predatory nature, wide environmental tolerance, and varied diet | 
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Aquatic invasive invertebrates
| Common name | Impacts | Click photo to learn more |
|---|---|---|
Bythotrephes longimanus (cederstroemii) | Spiny water fleas are a tiny freshwater zooplankton that invade lakes and can take over the bottom of the food chain. They can decimate populations of Daphnia and other native zooplankton resulting in a decreased food source for native fish and an increase in algal blooms. They can also clog the eyelets of fishing rods, causing problems for recreationalists. There are fewer predators on spiny water fleas than on native zooplankton because small or young native fish can’t consume their sharp, barbed spine. | 
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Dreissena polymorpha | Zebra mussels, though small, have huge impacts on our lakes. Their presence may greatly reduce lakefront property values and their sharp shells cut swimmer’s feet. Ecologically, they filter enormous quantities of microscopic algae and alter energy flow through aquatic ecosystems—impacting fish populations and smothering and causing extinctions of native mussels. | 
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Dreissena rostriformis | Quaggas are prodigious water filterers, removing substantial amounts of phytoplankton and suspended particulate from the water. Their impacts are similar to zebra mussels. By removing the phytoplankton, quaggas decrease the food source for zooplankton and alter the food web. | 
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Bithynia tentaculata | Faucet snails are an intermediate host for three intestinal trematodes, or flukes, (Sphaeridiotrema globulus, Cyathocotyle bushiensis, Leyogonimus polyoon) that causes mortality in ducks and coots. When waterfowl consume the infested snails, the adult trematodes attack the internal organs and cause lesions and hemorrhage. Faucet snails also compete with native snails and can clog water intake pipes. | 
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Orconectes rusticus | Rusty crayfish are very destruction of aquatic plant beds. They cause the aggressive displacement of native crayfish species and breed with native crayfish, replacing native crayfish populations with hybrids. They also compete with fishes for prey, and consumes fish eggs. | 
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| Signal crayfish Pacifastacus leniusculus | Signal crayfish prey on fish eggs and native wildlife, reduce invertebrate diversity, displace or eliminate native crayfish and amphibians, spread crayfish plague, and can contribute to riverbank erosion. | 
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Potamopyrgus antipodarum | New Zealand mudsnails outcompete native macroinvertebrate populations for food and habitat. They provide little nutrition to fishes that eat them. | 
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Chinese mystery snail, Japanese mystery snail, banded mystery snail | Competes with native snails for food and habitat. It can serve as a host for parasites that can be transmitted to fish and other wildlife. Banded mystery snails may invade largemouth bass nests and significantly increase the mortality rate of the eggs. | 
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| Golden clams Corbicula fluminea | Corbicula fluminea is an invasive freshwater clam that damages industrial water infrastructure, outcompetes native clams, and spreads easily through boats, ballast water, trade pathways, and natural water movement. | 
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| Freshwater jellyfish Craspedacusta sowerbii | The freshwater jellyfish may alter zooplankton community structure by preferentially preying on larger, predatory zooplankton. | 
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Harmful microbes
| Common name | Impacts | Click photo to learn more |
|---|---|---|
Viral hemorrahagic septicemia virus | As the name describes, the virus can cause internal and external bleeding which in severe cases leads to organ failure and death. | 
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Asian Fish Tapeworm (AFT) Schyzocotyle acheilognathi | Asian fish tapeworms parasitizes freshwater fish. The adult worm is an intestinal parasite in fish. Asian Fish Tapeworms can be spread by commercial carp and baitfish operations, such as grass carp pools, or Fathead Minnows or Golden Shiners. Fish infected with Asian Fish Tapeworms have been shown to have reduced ability to cope with stressors such as food availability. | |
| Tetracapsuloides bryosalmonae | Tetracapsuloides bryosalmonae is a myxozoan parasite of salmonid fish. It is the only species currently recognized in the monotypic genus Tetracapsuloides. It is the cause of proliferative kidney disease (PKD), one of the most serious parasitic diseases of salmonid populations in Europe and North America that can result in losses of up to 90% in infected populations. | |
| Largemouth Bass Virus (LMBV) | Largemouth bass virus (LMBV) is primarily a virus of largemouth bass, but more recently has been confirmed to also cause significant disease in smallmouth bass. | |
| Chytrid fungus Batrachochytrium dendrobatidis | Chytrid fungus is known to feed on living vertebrates. It primarily affects the skin of amphibians, causing the disease known as amphibian chytridiomycosis. | 
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Bacterial kidney disease (BKD) Renibacterium salmoninarum | Symptoms of BKD can include: abdominal fluid build-up and swelling; pseudomembranes on viscera; kidney and gill necrosis; hemorrhaging on viscera and in intestines; ulcers or abscesses in muscles; protruding eyeballs; anemia; blood blisters; and lesions of the eyes, liver, spleen, and heart (Austin and Austin 1987; Holey et al. 1998). | 
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| Yersinia ruckeri | Yersinia ruckeri is a bacterium that causes diseases in humans and other animals, including fish. Yersinia ruckeri is the causative agent of enteric redmouth disease in various species of salmonids worldwide. | 
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