By BLANCHE HARDY
The Lake Eustis Pupfish Cyprinodon variegatus hubbsi (Pupfish) is a shiny, small-bodied fish only found in eight lakes (Beauclair, Carlton, Dora, Eustis, Griffin, Harris, Yale and Weir) in the Upper Ocklawaha River drainage system of Central Florida. The Pupfish is a subspecies of the Sheepshead Minnow, a more prolific species readily found in estuaries along the east and west coasts of Florida.
As a result of their restricted range and vulnerability to habitat degradation, the Lake Eustis Pupfish was initially classified as a Florida threatened species. Subsequent research indicated that the Pupfish is relatively abundant within its range, allowing the fish to be reclassified yet remain part of the state’s Species Management Plan. Although tracked, the population status and extent of habitat used by Lake Eustis Pupfish is still poorly understood.
While the Pupfish is morphologically distinct (different in color and body shape) from the Sheepshead Minnow, it has yet to be classified as its own species. The fish developed as a residual of Sheepshead Minnows who occupied inland estuaries when parts of Florida were covered by seawater. As water receded, Sheepshead Minnows became landlocked. As the landscape continued to change from brackish water to freshwater, the isolated populations evolved a tolerance for inhabiting freshwater.
“Non-game fish like the Pupfish are often overlooked, yet they play an essential role in understanding ecosystem health,” said Ryan Howard, Associate Research Scientist of the Fish and Wildlife Research Institute Freshwater Fisheries Research of the Florida Wildlife Conservation Commission (FWC). “Because they aren’t targeted by anglers or commercial fisheries, their populations respond directly to environmental conditions. That makes them sensitive, early-warning indicators of things like shoreline integrity, water quality, habitat disturbance, and long-term ecological change”
During FWC’s last Pupfish assessment (2025), a total of 1,868 Lake Eustis Pupfish were collected across 12 monthly sampling events that took place between Feb. 26, 2025 and Feb. 10, 2026. FWC reported that Lake Eustis Pupfish abundance was highly variable across sites and sampling dates, ranging from 0 to 379 pupfish. However, the majority (70.1 percent) of Lake Eustis Pupfish were collected during the months of March (n = 510) and April (n = 799), with catch rates beginning to plateau in May. Of the pupfish collected, 73.7 percent (n = 1,377) were collected from sites with water temperatures in the range of 21.8 to 25.6°C.
Elevated nearshore abundance followed by a significant decrease, such as observed in the 2025 sample, suggests that pupfish move seasonally and may use alternative habitats depending on time of year, FWC scientists found. Biologists noted that Lake Eustis Pupfish collected in March and April appeared more colorful, with obvious orange margins along the pectoral fins and pronounced blue color around the head.
“Increased coloration and large, nearshore aggregations may indicate that Lake Eustis Pupfish use shallow, sandy bottom habitat with little vegetation to spawn throughout March and April,” Howard said. “Furthermore, the relatively low abundance of Lake Eustis Pupfish outside the months of March and April and their occurrence in November Black Crappie trawls suggest Lake Eustis Pupfish are using deep water habitats and potentially using this habitat type more frequently than shallow water.”
Along with their limited range, a number of characteristics make the Pupfish special. Their striking appearance helps them camouflage in the sands of their habitat and sand-burrowing behavior helps them avoid predators. Sand burrowing may also serve as a thermoregulation strategy.
Their nature to cluster to a small range of lakes in Central Florida is indicative of their genetically and geographically isolated lineage. And their survival in this narrow range and specialized ecological niche makes the Pupfish a biologically important example of localized adaptation and evolutionary change.
