Flatheads are not simple bottom feeders. Adults are highly predatory, their diet changes as they grow, and introduced populations have consumed recreationally important and conservation-sensitive fish.
Diet changes with size
Research describes a major transition around 300 millimeters—roughly 12 inches. Crayfish appeared most frequently overall in one Atlantic-river study, while sunfish contributed the greatest prey weight. Georgia reports that large flatheads over 500 millimeters are almost entirely fish-eating.
- Crayfish are especially important prey for smaller size classes.
- Native catfish and sunfish become vulnerable as flatheads grow.
- Larger predators can consume larger-bodied gamefish.
A wide menu
A recent study examined 576 flatheads, recovered identifiable contents from 241, and identified 47 prey species. Crayfish occurred in roughly 33.7% to 44.0% of diets depending on flathead size.
- Native catfish were documented as prey.
- Smallmouth bass became more likely in larger flathead stomachs in that study.
- Georgia confirmed a juvenile Atlantic sturgeon in a Satilla flathead stomach in 2010.
Potential consumption
One Atlantic-river study estimated daily ration at 3.06% of body weight per day in July and 7.37% in August under the conditions sampled. This illustrates high potential consumption during active feeding periods.