Flathead catfish

Flathead catfish spawn in cavities with male care, and their juveniles behave unlike other catfish almost immediately.

SPAWNING IS IN LATE SPRING AND SUMMER when water reaches a threshold temperature, later than most catfish in the same rivers.

THE NEST IS A SHELTERED CAVITY — a hollow log, an undercut bank, a crevice among rock or debris — which the male clears and then guards. Pairs spawn in the cavity, the female leaves, and the male tends the compact egg mass, fanning it constantly.

HE GUARDS AFTER HATCHING TOO, keeping the fry in a tight ball in the nest for a period, which is an unusually extended investment.

JUVENILES TURN PISCIVOROUS EARLY. Unlike channel or blue catfish, which are generalist scavengers for much of their lives, flathead catfish shift to eating live fish while still small, and adults are almost exclusively piscivorous and prefer live prey. That has consequences well beyond the fish itself.

WHICH IS WHY THE INTRODUCED POPULATIONS ARE A PROBLEM. Where flathead catfish have been introduced outside their native basins they have reduced native fish populations substantially, and they are managed as an invasive predator in several river systems rather than only as a fishery.

MATURITY IS AT SEVERAL YEARS, growth is fast in warm productive water, and the species is long-lived and reaches very large sizes.

Flathead catfish are strongly seasonal and their pattern is the opposite of the blue catfish that frequently share their rivers.

THEY FEED HARD IN WARM WATER AND BARELY AT ALL IN COLD. Activity rises sharply as water warms through spring, peaks through summer, and falls away in autumn. In winter flathead catfish become largely inactive, holding in deep cover and feeding minimally — which is why winter catfish fisheries target blues rather than flatheads.

SUMMER NIGHTS ARE THE PEAK. Flatheads are strongly nocturnal as adults, moving from daytime cover into shallower feeding areas after dark and returning before light. That daily movement is more pronounced in summer than at any other time.

THEY OCCUPY DEEP COVER BY DAY — log jams, undercut banks, rock and deep holes — and the same fish uses the same daytime cover repeatedly.

SPAWNING IN EARLY SUMMER interrupts the feeding pattern, with males occupying and guarding cavities.

FLOW EVENTS MOVE THEM. Rises in river systems shift fish and bring them onto feeding ground, and falling water concentrates them back into holes.

AND THE LIVE-PREY PREFERENCE IS A SEASONAL PRACTICALITY as much as a biological fact: it is why flathead fishing is a live-bait fishery in a way blue and channel catfish fishing is not, and why the season effectively follows the availability of the prey species they hunt.

The channel catfish account explains why ictalurid spines injure people: dorsal and pectoral spines lock rigid, so a hand closing on the fish drives them in. Flathead catfish present the same mechanism at a size where the forces are much greater.

WHAT CHANGES WITH SIZE. On a small catfish the spine is driven in by the angler's own grip. On a fifty-pound flathead the spine is driven in by the fish, and the wound is correspondingly deep. The venom associated with ictalurid spines produces disproportionate pain and the puncture is narrow, deep and hard to clean — the combination behind the high infection rate that makes catfish spine injuries a recognised presentation in emergency medicine.

THE GRIP IS DIFFERENT ON A LARGE FISH. The small-catfish grip from behind, palm under the belly with the pectorals between the fingers, does not scale. A large flathead is handled by supporting it horizontally with a hand under the belly forward of the pelvic fins and one supporting the tail region, or by lip-gripping the lower jaw — flatheads have no cutting teeth, only rasping pads, and lipping is genuinely safe on this species in a way it is not on most large predators. The pads will abrade skin over a long hold; they will not cut.

KEEP THE SPINES ORIENTED AWAY. The pectoral spines project laterally, which means they are pointing at whoever is standing beside the fish. On a boat that is usually somebody else.

AND THE FISH'S SIDE IS THE MASS. A large flathead held vertically by the jaw is unsupported, and the damage is internal. Horizontal support, wet hands, and back in the water quickly — these are warm-water fish often caught in high summer temperatures, when their tolerance for air exposure is at its lowest.