The upper reaches of the Chesapeake Bay system of estuaries are visited by many fish are normally considered to be freshwater species. Many of these fish are tolerant to some saltwater and thrive in tidal rivers, creeks and streams that empty into the Chesapeake.

The sunfish family (Centrarchidae) includes the several species of sunfish and bass that can be found in local waterways. The list includes bluegill sunfish (bream),  pumpkinseed, largemouth and smallmouth bass, black crappie and  white crappie.

Largemouth bass are one of the most familiar freshwater fish in North America. They are heavy bodied fish, instantly recognized by their mottled green sides, enormous mouth and plump bellies. They thrive in many of the rivers of the Chesapeake ecosystem, sharing habitats with species such as pike, pickerel, yellow perch, sunfish and catfish. Largemouth bass eat practically any other available fish species including their own.

Smallmouth bass are shaped similar to largemouth but tend to be smaller and favor slightly different habitats. The smallmouth bass derives its name from the fact that the rear end of the lower jaw does not extend past the eye, while that of a largemouth does. The usual smallmouth seen by anglers is 8 to 15 inches long, and weighs less than three pounds. The species is found in non-tidal stretches of the Potomac, Susquehanna and other rivers.

Bluegill sunfish (bream) are the most widely distributed panfish in the estuary. These colorful fish are well adapted to living in ponds, lakes, streams and even brackish water. Bluegill usually have a a black flexible tip on the gill cover. The gill cover is bright blue, giving the bluegill its name. The back and sides are dark green or brownish which is contrasted by a yellow, red or orange breast. Males in the breeding season have a dark red to mahogany colored breast. The sides of the fish usually display a series of vertical bars. Bluegill typically reach lengths of 7-9 inches.

Pumpkinseed are another common sunfish. Like bluegill, they are very deep-bodied. They are known for being one of the most colorful freshwater fish of the region, with males during the breeding season being the most colorful of all. Pumpkinseed have an orange or reddish breast and belly and its back and sides are brown to olive green, speckled with orange, yellow, blue, and green spots. The speckling of the flanks is interspersed with 7-8 dark vertical bands and narrow wavy stripes.

Pumpkinseed can be found in shallow areas with cool to warm water, primarily in the upper reaches of creeks and rivers. They associate with cover such as aquatic vegetation or submerged brush and are seldom found in open water. Pumpkinseed sometimes show a preference for a home range. When fish are captured and moved to a different part of a waterway, a significant percentage of them will return to their original location.

Crappie are also members of the sunfish family. Two species, black crappie and white crappie are found in rivers and creeks. The two fish are similar, with bodies having patterns of speckled black, silver, green and white. Crappie are typically pan sized, although they sometimes exceed 12 inches.

Yellow perch are found throughout the Chesapeake Bay Watershed. The yellow perch is a member of the perch family, which have a dorsal fin that is divided into separate spiny and soft-rayed portions. They are easily recognized by their orange fins and a body marked with vertical bars of alternating brown and yellow. Anglers gather in great numbers in the early spring when the fish school up before spawning. Yellow perch are caught all season, even in the winter in many of the rivers.

White perch are another panfish that is common in rivers and creeks of the Chesapeake Bay. Although smaller in size than striped bass, white perch  share a number of traits with their larger cousins.

The chain pickerel is common in creeks of the Chesapeake. The fish is named for its pattern of chain-like markings along the flanks of the fish. The species is a member of the pike family and relative of the muskellunge. Other distinctive markings include a black bar beneath its eye. It can be distinguished from grass pickerel by its chain pattern as the smaller grass pickerel exhibits dark vertical bars and rarely exceeds 10 inches. Like other pike species, chain pickerel prefer quiet areas of aquatic vegetation or other cover where they lie in wait to ambush unsuspecting prey.

The longnose gar is a living fossil whose family dates back millions of years. This odd-looking creature can be identified by its long narrow beak-like jaw, needle sharp teeth, long, cylindrical body, rounded tail fin, and large, bony scales. Longnose gar are found in brackish, slow moving rivers and creeks of the Chesapeake Bay Watershed.

The channel catfish is common in the Chesapeake Bay watershed. They usually weigh 2-4 lbs, occasionally reaching weights of 40 pounds or more. Channel catfish are easily distinguished from other species, except blue catfish, by their deeply forked tail fin. They are olive-brown to slate-blue on the back and sides, with silvery-white on the belly.

The blue catfish is a large, invasive catfish species.  Blue catfish grow to over 55 inches long and can weigh over than 100 pounds, living 20-25 years. Adults have stout bodies with prominently humped back in front of the dorsal fin. They have deeply forked tails similar to channel catfish, but lack spots and have a large straight edged anal fin. The back and upper sides are blue to slate gray, and the lower sides and belly are white.

The white catfish is another species found in rivers and creeks of the Chesapeake Bay. White catfish are bluish-gray with white undersides, broad head, large mouth, stout build and moderately forked tail. Their white chin barbells distinguish it from other species of catfish. White catfish occasionally reach lengths up to 24 inches and weigh 6 pounds but a typical fish is around 12-14 inches.

Several species of bullhead catfish occur in Chesapeake Bay rivers. They are similar in appearance, but easy to distinguish from non-bullhead species due to their squared tail and stocky build. Black bullhead have dark chin barbels and lack mottled markings on their sides. Brown bullhead have mottled sides and light margins on their fins. The common yellow bullhead are distinguished from other species of bullhead by their yellow or off-white chin barbels. Black, Brown and Yellow bullhead catfish prefer slow moving or still waterways but will tolerate a variety of habitats, including muddy water and low oxygen levels.