Taxonomy & naming
Elassoma okefenokee was described by James E. Böhlke in 1956 from the Okefenokee Swamp region of southern Georgia and is the type species most closely tied to that name. It belongs to Elassomatidae, the pygmy sunfishes, a family that contains only the single genus Elassoma. "Pygmy sunfish" is a common-name convenience rather than a claim of close kinship: the family has traditionally been classified alongside the true sunfishes (Centrarchidae) on the strength of shared spiny-rayed fins and superficially similar body shapes, but molecular studies have proposed other placements for the group, and its exact position among the spiny-rayed fishes is still debated among ichthyologists.
For decades, fish recorded as Elassoma okefenokee across its range — from the Okefenokee basin south through much of peninsular Florida — were treated as one species. In 2009, taxonomists split the Florida populations into a separate species, E. gilberti, leaving E. okefenokee as the form centered on the Okefenokee Swamp and the Georgia and northern Florida drainages that flow from it. Older hobby and survey records that simply say "okefenokee" from central or southern Florida localities may therefore refer to either species.
Morphology
This is a genuinely tiny fish: FishBase lists a maximum length of about 1.5 in total length, with most adults closer to 1 in. The body is short, deep-bodied for its size, and ends in a distinctly rounded caudal fin rather than the forked tail typical of larger perciform fishes. Like other pygmy sunfishes, it lacks a functional lateral line, one of the family's defining traits, and instead relies on other senses to navigate the dense cover it lives in.
Coloration is strongly seasonal and sex-linked. Females and nonbreeding fish of both sexes are cryptic — a mottled olive-brown that blends into leaf litter and plant stems, with faint dark bars along the flank. Breeding males transform: the body darkens toward black, set off by rows of pale, iridescent blue-green flecks and bars, and the fins lengthen and darken to match. The contrast between a drab autumn fish and a jet-black, flash-marked breeding male is one of the most striking displays among small North American natives.
Habitat
Elassoma okefenokee is found from the lower Altamaha River drainage in Georgia south into central peninsular Florida, and west to the Choctawhatchee River drainage. Within Georgia it has been recorded in the Suwannee, St. Marys, Satilla, and Ocmulgee river basins; in Florida it occupies interior lake basins in the north-central part of the state as well as the upper Suwannee, Withlacoochee, and Hillsborough drainages on the Gulf Coast side.
Its habitat is the swamp itself: heavily vegetated sloughs, backwaters, and small, sluggish, tannin-stained streams over soft mud, the kind of blackwater conditions the Okefenokee is known for. Reported water conditions span a wide seasonal range, from around 39 °F in cold snaps up to roughly 86 °F in summer, with pH from about 6.0 to 8.0 and soft water. That tolerance for cold reflects a climate with real winters, not the tropical warmth most aquarium fish need.
Feeding
Elassoma okefenokee is a micropredator, picking small aquatic invertebrates — microcrustaceans such as copepods and cladocerans, and the larvae of aquatic insects — from among plant stems and detritus rather than chasing prey in open water. In the aquarium it does best on live or frozen foods sized to match its small mouth: grindal worms, live blackworms or California blackworms, thawed bloodworm, Daphnia, microworms, and newly hatched brine shrimp. Some individuals learn to take crushed flake, but dry food is not reliable as a primary diet and most keepers treat this species as a live-food specialist.
Mating
As spawning approaches, a male stakes out a small patch of dense vegetation and takes on the family's characteristic breeding dress — the body darkening toward black and marked with pale blue-green flecks — a signal that also functions as a display to females moving through the cover. Courtship plays out among the plant stems the male has claimed, with females that enter his patch cued by the same dark coloration and pattern that make him conspicuous against the foliage.
Because the species spends its whole life in dense vegetation, courtship and spawning happen largely out of sight, and much of what is documented about the behavior comes from aquarium observation rather than field study.
Breeding
Eggs are deposited singly or in small groups directly onto fine-leaved aquatic plants; aquarists breeding the species have had good results providing strands of coontail (Ceratophyllum), and spawning can be repeated over consecutive days as the female releases more eggs. The species does not need a large setup to breed — a well-planted tank of as little as about 5 US gal has been reported sufficient.
Parental care in Elassoma okefenokee specifically is not well documented; a related species, E. evergladei, is known to have males guard the eggs, but this has not been confirmed for E. okefenokee. Clutch size, incubation time, and typical lifespan have likewise not been established for this species in the sources reviewed here, and figures sometimes quoted for other Elassoma species should not be assumed to apply directly.
In the aquarium
Elassoma okefenokee suits a cool, densely planted species tank rather than a conventional heated community aquarium. Given the wide seasonal temperature range it tolerates in the wild, it does not need — and often does not want — tropical heat; many keepers run it unheated at room temperature. A thick stand of Java moss or other fine-leaved plants is close to a requirement, both as cover for a fish this small and as the substrate it will use for spawning.
Because of its size and its dependence on live foods, it is not a community fish: it is too small and too slow a feeder to compete with typical tropical tankmates, and it is itself small enough to be eaten by almost anything larger. Small shrimp and snails make workable tankmates; fast or predatory fish do not. Keepers should be prepared to culture or regularly source live foods, since dry food alone is not adequate.
Conservation
The IUCN Red List classifies Elassoma okefenokee as Least Concern. A significant part of its core range lies within the Okefenokee National Wildlife Refuge, which affords its primary habitat some protection from direct development. Reported threats to the species elsewhere in its range center on habitat degradation and the spread of invasive species in the small blackwater streams and swamps it depends on.
No federal Endangered Species Act listing or specific state-level protected status was identified for this species in the sources reviewed here.