Redeye Bass

A fish of one drainage, above one line

The redeye bass is a creature of the Alabama and Georgia uplands, and specifically of the country above the Fall Line — the geological seam where the hard rock of the Piedmont gives way to the sands of the Coastal Plain. Above that line, streams run over bedrock and cobble, drop through shoals, and hold cool clear water. Below it they slow, warm and silt. The redeye bass belongs entirely to the first kind of water.

Alabama’s Department of Conservation and Natural Resources describes it as endemic to the Mobile Basin, occurring above the Fall Line in the Coosa and Tallapoosa river systems, and as a fish that “inhabits small to medium-sized upland streams and only rarely large rivers and impoundments.” That last clause is the whole story of the species compressed into one sentence. A fish that rarely uses impoundments has nowhere to go when its river becomes one.

The current taxonomy narrows the range further still, and it is worth being plain about the disagreement rather than smoothing it over.

One species became seven

For most of the twentieth century, “redeye bass” meant a single species, Micropterus coosae, described by Hubbs and Bailey in 1940 and understood to occupy upland streams across a broad sweep of the Mobile Basin and beyond. That arrangement no longer holds.

In 2013, Baker, Blanton and Johnston, writing in Zootaxa, described four new species out of what had been called redeye bass: Micropterus cahabae (Cahaba bass), restricted to the Cahaba River system; Micropterus tallapoosae (Tallapoosa bass), restricted to the Tallapoosa; Micropterus warriorensis (Warrior bass), in the Black Warrior; and Micropterus chattahoochae (Chattahoochee bass), in the Chattahoochee. They separated the group on pigmentation, scale counts, development of the tongue tooth patch, and divergence in the ND2 gene. The paper is explicit about what was left: Micropterus coosae is now “restricted to the Coosa River system.”

The 2022 phylogenomic revision by Kim, Taylor and Near in Scientific Reports went further, using ddRAD genomic data to recover nineteen species of Micropterus — fourteen described, plus the undescribed but well-known Altamaha, Bartram’s and Choctaw basses, plus two undescribed lineages currently filed under smallmouth bass. That work places seven species in the redeye bass complex: redeye, Cahaba, Chattahoochee, Tallapoosa and Warrior basses, plus the still-undescribed Altamaha bass and Bartram’s bass. Some of these lineages are genetically very close — the paper reports the Cahaba bass and redeye bass as the least divergent pair in the whole genus.

Agencies have adopted this at different speeds, and the resulting inconsistency is real. Georgia’s Department of Natural Resources lists redeye bass, Chattahoochee bass, Tallapoosa bass, Altamaha bass and Bartram’s bass as five separate fish in its identification guide, and its Georgia Bass Slam treats them as ten distinct black bass species statewide. Alabama’s species page still describes redeye bass as occupying both the Coosa and Tallapoosa. South Carolina’s Department of Natural Resources lists its Savannah-basin fish as Micropterus coosae while noting in the same page that “ongoing research indicates the fish in South Carolina and parts of Georgia is actually a separate, not yet described species, sometimes referred to as Bartram’s bass.”

The practical consequence is that a fish called “redeye bass” in a South Carolina reservoir, a Georgia Piedmont creek and an Alabama Coosa tributary may be three different species, and only the last is Micropterus coosae.

The other redeye: a shared nickname for a different fish

There is a second, older confusion that predates all of this and has nothing to do with genetics. Across much of the eastern United States, “redeye” is a common vernacular name for the rock bass, Ambloplites rupestris — a different genus in the same family. Ohio’s Department of Natural Resources lists rock bass as also known as “goggle-eye” and “red-eye,” and describes it as a red-eyed, large-mouthed sunfish of clear rocky streams — the same habitat description that fits redeye bass, which is why the names collided in the first place.

The two are easy to separate once looked at. Rock bass carry six anal spines against three in the black basses, show a dark teardrop mark under the eye, and have black fin margins. Redeye bass have the white-edged tail described below. Reports of “redeye” from the Ohio, Tennessee or upper Mississippi drainages are almost always rock bass; Micropterus coosae does not naturally occur there.

Identification

Geography is the first and best filter. In its native range, redeye bass share water with Alabama bass and largemouth bass but not with shoal bass or Suwannee bass, whose ranges lie in different basins entirely. Once a fish is in hand, a short list of characters settles it.

• Caudal fin margins. Alabama DCNR’s most useful single character: “The upper and lower margins of the caudal fin are edged in white.” Shoal bass lack this. It is the quickest field separation between the two.
• Tongue tooth patch. Redeye bass carry teeth on the tongue. Alabama’s shoal bass page uses their absence as a diagnostic against redeye bass. Spotted and Alabama bass also carry a tongue patch — Florida FWC describes it as rectangular — so the patch separates redeye from shoal and largemouth, not from spotted.
• Jaw against eye. The redeye’s upper jaw extends to or slightly behind the rear margin of the eye. Largemouth bass jaws extend clearly beyond it; FWC pairs that with an obvious deep notch between the dorsal fins. Redeye bass have connected dorsals and no deep notch.
• Fin counts. Dorsal fin with nine to eleven spines and eleven to thirteen rays; anal fin with three spines and nine to eleven rays.
• Lateral-line scales. Scale counts are the workhorse character across the genus and were part of what separated the four new redeye-complex species in 2013. For comparison in Alabama waters, spotted bass in the upper Mobile Basin run 68 to 77 lateral-line scales and the Tennessee River form 58 to 71, while smallmouth bass run 68 to 80.
• Colour. Olive to brown back with darker brown mottling, and horizontal rows of dark spots along the lower sides. Red or reddish eyes and reddish fins are typical but not reliable on their own — smallmouth bass eyes also carry a reddish tint.

What none of these characters will do is separate M. coosae from Cahaba, Tallapoosa, Warrior or Chattahoochee bass in the field with confidence. Those splits rest on subtle pigment and scale differences and on genetics. Drainage of capture is the honest answer.

Habitat and water temperature

Redeye bass occupy small to medium upland streams with aquatic vegetation, submerged stumps, boulders or undercut banks. They are current-oriented and rock-oriented, holding on structure that breaks flow.

Because these are headwater streams, thermal behaviour is fast and local. A shallow Coosa tributary can gain ten degrees over an afternoon and shed it overnight, and the same stream may hold water in the fifties in March and the eighties in August. Shaded runs, spring seeps, deep plunge pools and the mouths of cold tributaries become refuges as summer builds. Live temperature at a gauge is the most useful single number available for reading these streams, and it moves far more than it does on a big impounded river.

Flow regulation compounds the temperature question. Earley and Sammons, in River Research and Applications, examined how hydropeaking operations affect the growth of Alabama bass and redeye bass in the Tallapoosa River — a reminder that in regulated reaches both the thermal and the hydraulic regime are set by a dam schedule rather than by weather.

Spawning, growth and feeding

Spawning runs from April through June in Alabama, on the rising water temperatures of mid-spring. Recorded lifespan is nine to ten years, which is long for a fish this size and consistent with slow growth in cool, nutrient-poor upland water. Lewis and colleagues published age and growth data for the redeye bass complex across the Mobile River basin in the North American Journal of Fisheries Management in 2025, treating the complex as the set of species it is now understood to be.

The diet is what an upland stream provides: aquatic and terrestrial insects, crayfishes and small fishes. The terrestrial component matters — redeye bass in small streams take a substantial share of their food from the surface, and from things that fall in.

The species also makes noise. Johnston and colleagues documented acoustic signals produced during aggression in what they called Coosa bass, in Environmental Biology of Fishes.

Conservation: hybridization, impoundment, and a fish moved around

The IUCN lists Micropterus coosae as Least Concern, but that assessment dates to 2012 and was made against the old, broad concept of the species. Cutting the range down to the Coosa system alone, as the current taxonomy does, has not been reflected in a reassessment. Baker and colleagues noted in 2013 that three of the newly described species — Warrior, Cahaba and Chattahoochee basses — are uncommon and may need conservation attention.

The most active threat is genetic. Introduced Alabama bass hybridize readily with redeye-complex fish. Barwick and colleagues documented redeye bass and Alabama spotted bass hybridization in Keowee Reservoir in Southeastern Naturalist, and Peoples and colleagues modelled the distribution of Bartram’s bass in the North American Journal of Fisheries Management, finding that disturbance and proximity to the invasion source both increase hybridization with invasive Alabama bass. South Carolina’s agency states the problem directly: introduced smallmouth, spotted bass and their hybrids “pose a significant threat to redeye bass throughout its range in South Carolina.”

Redeye bass have also been the invader. Lewis and colleagues found genetic evidence of introduced redeye bass and Alabama bass hybridizing with native Micropterus in Town Creek, Alabama — a native species turned into a genetic problem by being moved outside its drainage. Populations well outside the Mobile Basin, including in the Savannah drainage and in California, trace to stocking.

Impoundment does the slower damage. A fish that rarely uses reservoirs loses habitat outright when a shoal becomes a lake, and the remaining stream populations are left fragmented above and below the dam, unable to recolonize each other after a drought or a spill.

Angling character

Redeye bass are small fish that fight above their weight, and the fishery reflects that. Alabama DCNR calls the species “an excellent game fish, especially when taken on ultralight spinning tackle or a fly rod” — a description that comes from the scale of the water as much as the fish. These are wadeable creeks, sight-fishable in low clear water, and the fish sit where current meets structure.

The seasonal pattern follows temperature closely. Fish spread out and feed hard through the spring warm-up and again in autumn, and pull back into shade, depth and cold-water seeps through the hottest part of summer. The state record — 3 pounds 2 ounces from Choccolocco Creek in 2000, per Alabama’s state record list — sets a realistic ceiling on expectations. This is not a species where size is the point.