July 2002: Flathead catfish, which are native to western Pennsylvania waters, have been caught in the Susquehanna and Schuylkill River drainages in recent years. In July 2002, a number of small flathead catfish were caught downstream of Safe Harbor Dam. Based on the observation of flathead catfish populations observed thus far in the Delaware River Basin and Schuylkill River Basin, it is expected that these fish will become part of the fish community in the Susquehanna. Their populations should not be overwhelming. The source of the flatheads found in the Susquehanna River is unknown.

Flathead catfish populations were identified in Southeastern Pennsylvania in 1997 at Blue Marsh Reservoir. Based on the age and size of the fish taken at Blue Marsh, it likely they had been in the reservoir for some time. Flathead have also been seen in several other impoundments and in the Schuylkill River and Delaware River. Reproducing populations of flathead catfish have been documented in the Schuylkill River Basin. A few flathead catfish have been reported from the Fairmont Dam fishway on the Schuylkill River each year since 1999. The current populations in the Schuylkill River Basin and Delaware River Basin are sparse, but a directed fishery is developing on sections of the Schuylkill and Springton Reservoir.

The flathead catfish is not a new species of fish to Pennsylvania, but the presence of these fish in river basins where they have not occurred in the past is a matter of interest and some concern (view our Aquatic Invasive Species page for more).

On western Pennsylvania waters where these fish are native, anglers find flatheads an attractive sport fish and good table fare. Although angling is not expected to eliminate or control abundance of flatheads in the eastern Pennsylvania waters where they have now been found, anglers can help. If anglers catch flathead catfish in the Susquehanna or Schuylkill River basins, they are encouraged to take them and not release them, regardless of size. Flathead catfish are subject to the same regulations as other catfish covered by Commonwealth Inland Regulations -- no minimum size limit, 50 per day creel limit and no closed season. [Click here for a 2002 article on flathead catfish in the Delaware River Watershed from Pennsylvania Angler & Boater magazine]

Species overview:  Flathead catfish are native to the lower Great Lakes and the Mississippi River basin, from western Pennsylvania southward. They are also in Gulf of Mexico watersheds, and can live in reservoirs. In Pennsylvania, flatheads are found mainly in the Ohio, Allegheny and Monongahela rivers. Fossils of this catfish genus that are about 15 million years old, from the mid-Miocene Epoch, can’t be distinguished from the modern flathead catfish. The flathead’s genus name “Pylodictis” means “mud fish,” and its species name “olivaris” means “olive-colored.”

Identification: Flathead catfish grow longer and heavier than other Pennsylvania catfish. The Pennsylvania record is over 40 pounds, but flatheads in the size range of 20 or 30 pounds are more likely to be found in Pennsylvania. In more southern climates, flatheads as big as 90 to 100 pounds have been documented.

Flathead catfish have the scaleless, strong body and the well-developed pectoral and dorsal fin spines typical of catfish. The lower jaw of a flathead projects past the upper jaw. This feature is the key characteristic that helps anglers and others distinguish the identify of flatheads from other eastern Pennsylvania catfish. The dorsal fin is high. The tail is only slightly indented, or may appear square or rounded. The body looks long and slender. The upper portion of the flathead catfish’s body is yellowish brown to dark, even purplish brown, with black or brown mottling on lighter brown sides. The belly is grayish or yellowish white. It does have a flat-looking head, very wide and depressed. The chin barbels are white to yellow, the fins are mottled, and the anal fin, which has fewer than 16 rays, is short and rounded. Except for very large adults, flathead catfish have a white tip on the upper lobe of the caudal fin. Young flathead catfish are nearly black on the back.

Habitat: Flathead catfish are found in large rivers, streams and lakes, usually over hard bottoms. They prefer deep, sluggish pools, with logs and other submerged debris that can be used as cover. Young flatheads live in rocky or sandy runs in the river and in the riffles.

Life history: The flathead is a loner and a traveler, leading a solitary existence except at spawning time. Flatheads spawn in early summer, later than channel catfish. The flathead’s spawning behavior is like that of other catfish. The adults form pairs and build nests in natural cavelike depressions in the bank, or they may hollow out a cavity under an underwater object, like a log or boulder. Their compact egg masses contain from 4,000 to 100,000 eggs. The male guards the nest and the newly hatched fry, becoming aggressive toward the female.¹

Flatheads grow fairly rapidly and mature sexually at about 15 inches and five years old. They can live to at least 19 years old. Juvenile flatheads live in riffle areas and feed on larvae and nymphs of aquatic insects. As the flathead grows, it switches to crayfish and fishes, although many items are on its menu. During the day, flathead catfish stay out of sight, hiding beneath undercut banks, in brush piles and log jams. At night they forage in a variety of habitats, including very shallow riffles where their backs and dorsal fins may be exposed. For this reason, angling at night with live fish or crayfish as bait is the way to catch a big flathead. Biologists report that one possible feeding strategy of the flathead is to lie motionless with its mouth open, until a fish looking for a spot in which to hide swims in. Others have observed flatheads lunging and grabbing prey after they have lain in wait.

1. Some recent research using telemetry has challenged the common understanding of the life history of flatheads. Flatheads are often portrayed as sedentary, freshwater restricted fish existing in low density populations. Research in the Southeastern states using telemetry and population estimation techniques has revealed some populations in densities estimated to be 100-400 per stream or river kilometer, movement of up to 30 kilometers in just a few months, and a tolerance for brackish water with salinities of 6 parts per thousand.

-- source: Tom Qwak, Ph.D, Unit Leader, NC Cooperative Fish and Wildlife Reseach Unit

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