From its headwaters in South-Central Wisconsin near Pardeeville, the Upper Fox River meanders through the charming city of Portage before eventually flowing northeasterly into Lake Winnebago — the largest lake contained within the state. The Lower Fox River begins on the north end of the lake, then flows toward Appleton before dropping into Green Bay where it reaches Lake Michigan.
At approximately 200 miles in length, the Fox River hosts a chain of small cities, towns, and villages along its banks which are sometimes referred to as the Fox Cities. Carved by the movements of the Laurentide Ice Sheet some 10,000 years ago, parts of the Fox River are surrounded by ridges that are remnant glacial moraines.
Despite lingering concerns over pollution in some areas, today the Fox River area remains popular for recreation of many kinds, including hiking, boating, and of course, fishing — though consumption of fish from certain parts of the Lower Fox is not recommended. The following list describes some of the most common fish that can be found in the Fox River.
Fish Species in the Fox River
1) Walleye (Sander vitreus)
Family: Percidae
Other names: Yellow pike, yellow pickerel
Named for their opaque or cloudy eyes, walleye have a reflective pigment in a thin layer of eye tissue called the tapetum lucidum, which helps them see well in low light. Walleye have a streamlined body and can be identified by their dark olive-brown to yellow-gold color, with brassy flecks on the side. Unlike other similar-looking fish like sauger, walleye have a dark area at the base of the dorsal fin but lack spots on the dorsal fin itself. They also usually have a white spot on the bottom of the tail.
Walleye can weigh up to 20 pounds, with state regulations in most areas requiring that kept fish be at least 15 inches long. In Wisconsin, the walleye is considered a prize game fish, often captured during their spring spawning runs. Walleye are also a popular target for ice fishing. The taste is described as subtle and sweet with very few bones, making it a favorite of the famous Wisconsin Friday fish fry.
Due to their sensitive vision, walleye generally prefer deeper water, avoid bright light, and often feed at night. Though night-fishing efforts may be successful, fishing after sunset is prohibited during certain time periods, and night boating may have speed limits in certain areas in Wisconsin. The Fox River is a popular place to catch walleye, especially in the early spring, with many fish exceeding 10 pounds. Size limits are in place during certain times of the year to protect spawning females, especially due to recent walleye population declines attributed to increasing water temperatures, overharvesting, and habitat loss.
2) Yellow perch (Perca flavescens)
Family: Percidae
Other names: American perch, lake perch, Dodd fish
Yellow perch have an elongated oval body with a blunt snout and two dorsal fins. They range in color from golden yellow to olive green, typically with six to eight vertical darker bars on the side of the body. The underside is lighter in color, with pectoral fins that may be orangish or amber. Yellow perch are small, with record fish just over four pounds, and are considered a “panfish” with a high daily bag limit compared to larger species.
These fish are native to North America and serve as an important food source for other larger fish like walleye and bass. Yellow perch are primarily bottom feeders, consuming aquatic invertebrates and smaller fish. They can typically be found along the shore, preferring cover such as reeds, aquatic vegetation, or human-built structures. Baits including minnows, insect larvae, and nightcrawlers are usually highly successful. As these fish move in schools, several can often be captured in a single location.
Many yellow perch enter the Fox River in the early spring for spawning, with the high season from January to March and July to December. Though small in size, yellow perch are popular for their mild, sweet flavor and are frequently used in fish fries. As yellow perch populations have declined in Lake Michigan, statewide assessments in Wisconsin continue to monitor these fish.
3) Smallmouth bass (Micropterus dolomieu)
Family: Centrarchidae
Other names: Bronzeback, brown bass, smallie, bareback bass
Another popular game fish described as the “scrappiest” in the state, the smallmouth bass can be identified by its golden-olive to dark brown colors and dark brown vertical bars or blotches along the body. Unlike the similar largemouth bass, the jaw of the smallmouth bass does not extend past the eyes. These muscular fish can typically weigh from two to six pounds, with females having a larger body size. They are often found in clear, cool water — especially where crayfish are abundant — and their intolerance of pollution makes them a good biological indicator of a healthy environment.
Smallmouth bass can be captured using baits such as hellgrammites and crayfish imitations, with light tackle strategies recommended. In Wisconsin, using live crayfish is illegal in inland waters except for the Mississippi, so these cannot be used in most areas including the Fox River. Smallmouth bass are susceptible to largemouth bass virus, an infectious disease that causes skin lesions, and have tested positive in Wisconsin. As such, general practices for reducing the spread of aquatic invasive species, such as draining all water from boats and equipment and not moving live fish between bodies of water, are encouraged throughout the state.
4) Muskellunge (Esox masquinongy)
Family: Esocidae
Other names: Muskie, lunge
The largest member of the pike family and the state fish of Wisconsin, the name of the muskellunge originates from Ojibwe words meaning “great fish” or “big ugly pike”. These fish are ambush predators with elongated brown bodies marked with dark bars or light spots, though some may have very faint markings. They can be distinguished from similar species like the northern pike by the presence of seven or more sensory pores on the underside of the mandible, as well as by the presence of scales only on the upper half of the cheek and operculum. The paired fins and caudal fin are pointed at the tips.
Muskies are generalist predators, consuming a variety of other fish as well as insects, muskrats, rodents, frogs, and waterbirds. These aggressive fish are occasionally reported to attack dogs and even humans, though the extent and severity of reports are likely exaggerated. Trolling artificial lures from slow-moving or drifting boats is a popular method for catching muskies.
Due to their large size — the state record fish was nearly 70 pounds — muskies are especially prized as trophies. They can be eaten, but limited quantities are recommended since apex predators can bioaccumulate toxins such as mercury, so catch-and-release is often more common for this fish species. Following water clean-up efforts and stocking initiatives, muskies now thrive in Green Bay and in the Fox River.
5) Northern pike (Esox lucius)
Family: Esocidae
Other names: Common pike, jackfish, pickerel
A close relative of the muskellunge, the northern pike is similar in appearance but typically smaller. They can be identified by their olive-green color with lighter markings, which are typically horizontal oval shapes. The tips of the forked tail and paired fins are rounded, and there are never more than six sensory pores on the underside of the mandible. Hybrids between muskellunge and northern pike can be found in the Great Lakes and some other regions, and are referred to as “tiger muskellunge” as a reflection of their alternating pattern of stripes and spots. The silver pike is another form of the northern pike, which is silvery or white and lacks spots due to a mutation that occurs in certain populations.
Northern pike are ambush predators that mostly consume other fish, including instances of cannibalism among younger fish. Northern pike are most active in cooler water, preferring live baits and wobbling spoons. Ice fishing, shore fishing, trolling, and fly fishing are common techniques for catching northern pike. These fish can be eaten but are considered bony, and like other apex predators, frequent consumption is not recommended due to bioaccumulation of contaminants including per- and polyfluoroalkyl substances. Many are caught and released, though caution should be used to avoid their sharp teeth while removing a hook. They are also sensitive to dry hands and do not tolerate being out of the water for very long, so should be handled carefully.
6) Channel catfish (Ictalurus punctatus)
Family: Ictaluridae
Other names: Spotted cat, Great Lakes catfish
One of two catfish species in Wisconsin, the channel catfish is a large, scaleless fish with a blue to olive back and a lighter belly with silvery sides. It is the only catfish species with distinctive black spots, though these spots may disappear in older males. The caudal fin is deeply forked, and the fish rarely exceeds 30 pounds. Though both the channel catfish and its larger relative — the flathead catfish (Pylodictis olivaris) — can be found in the Mississippi, Wisconsin, and Fox River systems, the channel catfish has a wider range and is much more abundant in Wisconsin. The flathead catfish can also be identified by its flatter head, protruding lower lip, and square caudal fin.
As the most frequently eaten catfish in North America, the channel catfish is popular among anglers and as a farmed fish. These fish are generalists, consuming other fish, crustaceans and other aquatic invertebrates, snakes, frogs, aquatic plants, algae, and occasionally birds or small mammals. They thrive in rivers and tolerate higher water turbidity than other gamefish, though they prefer cool, clear, slow-moving waters. Dark, deep pools beneath dams or with submerged logs or rocks also provide excellent habitat for these fish.
As they are adapted for the dark, with highly refined senses of smell, taste, and hearing, they often feed at night. They will take nearly anything as bait, including strips of meat, nightcrawlers, doughballs, and even soap, but the odors of homemade or store-bought “stink baits” are often reported as the most successful. Fishing a few days after rain can also increase the chances of catching a channel catfish.
7) Gar (Lepisosteus spp.)
Family: Lepisosteidae
Other names: Garpike
Gar are an ancient group of fish that first appeared over 240 million years ago, with a body type that has changed very little over time. The seven extant species are native only to North America, east of the Rockies. They are easily identified by their elongated bodies and long jaws full of sharp teeth. Two species are found in Wisconsin: the longnose (Lepisosteus osseus) and shortnose gar (L. platostomus). The longnose gar is brown to olive green in color, sometimes with black spots, with a needle-like snout at least twice as long as its head. In comparison, the shortnose gar is more variable in color with a shorter, broader snout.
These living fossils can be found in brackish waters of the eastern United States, including the Mississippi, Wisconsin, and Fox River systems. Due to their vascularized swim bladders, like other gars, these species can breathe oxygen from the air directly and from the water via gills. Their diets include small fish, insects, and crustaceans, which they mostly consume at night. Both gar species have a long lifespan of approximately 15 to 20 years.
The Wisconsin state record longnose gar was just over 21 pounds while the state record shortnose gar — caught in the Fox River — was just over 4 pounds. Due to their thick, scaly armor, gar have few natural predators, though they are sometimes caught for sport and are edible, with a flavor and texture usually compared to alligator or chicken.
8) Lake sturgeon (Acipenser fulvescens)
Family: Acipenseridae
Other names: Rock sturgeon
Like gar, the lake sturgeon is an ancient fish that has existed in a similar form since the time of the dinosaurs. They are the oldest and largest native fish found in the Great Lakes, capable of measuring more than six feet in length and weighing more than 200 pounds. They have a robust, torpedo-shaped body that is brown to gray in color, with barbels near the sucker-like mouth that are used to slurp up live food. Sturgeon lack teeth, and therefore mostly consume insect larvae, worms, and other small organisms.
Lake sturgeon can be found throughout the Mississippi drainage basin and most of the areas that were once linked by the large lakes that formed after glaciers retreated at the end of the last ice age. They have a long lifespan, with females living in excess of 100 years.
Though initially considered pests and slaughtered en masse by European colonizers, sturgeon later became prized for their eggs which can be eaten as caviar. In combination with increased unsustainable harvesting, as well as industrialization and pollution associated with the paper mill industry, by the early 1900s, the lake sturgeon reached the verge of extinction. However, in response to conservation and restoration efforts, lake sturgeon numbers have been slowly increasing.
Limited recreational fishing, with a bag limit of 1 lake sturgeon per season, is permitted in some locations in Wisconsin, Michigan, and Minnesota — including in Lake Winnebago. Along the lower Fox River and several other locations, lake sturgeon spawning can be observed from mid-April to early May.
9) American gizzard shad (Dorosoma cepedianum)
Family: Clupeidae
Other names: Mud shad
A member of the herring family, the American gizzard shad is a deep-bodied, silvery fish found throughout much of eastern North America. Their name refers to their gizzard, which is a sack filled with rocks or sand that aid the fish in mechanically digesting food. They may have been native to Lake Erie prior to the 1800s but were not commonly found elsewhere in the Great Lakes until the early 1900s, suggesting that they were introduced or that their movement was facilitated by human activities.
These fish primarily feed on zooplankton, especially Daphnia, but will also eat phytoplankton, detritus, and small crustaceans. They are primarily active during the day, preferring shallow lakes with high turbidity. Gizzard shad are important prey for other fish like walleye and bass, but grow quickly and can eventually become inaccessible to these predators and thereby may outcompete other fish species.
Gizzard shad are intolerant of cold temperatures, with large die-offs often occurring in the winter in Wisconsin. In doing so, however, these mass die-offs of shad provide food for lake sturgeon, which opportunistically feed on them in the winter months. Though gizzard shad are edible and can exceed 3 pounds, they are considered smelly, oily, and bony, and as such are not frequently consumed but rather are usually used as bait for other fish.
