Why This Tiny Tennessee Fish Is on the Brink of Extinction

Native to the streams in the Collins River watershed on the Barrens Plateau, which runs through Cannon, Coffee, Grundy, and Warren counties in Middle Tennessee, the Barrens darter (Etheostoma forbesi) is one of the most geographically isolated freshwater fish species in North America. Decades of monitoring provide ample evidence that Barrens darter populations have experienced a significant decline in the face of multiple threats. Many populations have already been lost, and the remaining ones are small and fragmented. As such, on July 1, 2025, the U.S. Fish and Wildlife Service published a proposal in the Federal Register to list the Barrens darter as an endangered species. Continue reading to learn more about Tennessee’s unique little fish and what is driving it to the brink of extinction.

Barrens Darter: Overview

The Barrens darter was formally described in 1992 by Lawrence M. Page and Patrick A. Ceas. The first specimens were collected from Duke and McMahan creeks and their tributaries in Cannon County, Tennessee. The fish that are now recognized as Barrens darters were previously misidentified as blackfin darters (Etheostoma nigripinne), fringed darters (Etheostoma crossopterum), or spottail darters (Etheostoma squamiceps).

The Barrens darter is a small, bottom-dwelling fish that averages 2.9 inches in length and weighs less than one ounce. It has a tawny color with brown mottling. Its average lifespan is three years, though some individuals may live up to four years. They reach sexual maturity within their first year of life.

After establishing a territory under a rock, a male produces sounds to attract a mate. Once a pair mates, the female deposits her eggs on the underside of the rock. The number of eggs in a clutch varies widely, from fewer than 100 to almost 1,000. After laying the eggs, the female leaves and provides no further care. The male then guards the nest, protecting the eggs until they hatch. This type of exclusive paternal care is observed across the subgenus Catonotus, in which the Barrens Darter is contained.

Predators and Threats

Dedicated monitoring and routine surveys have determined that two of the Barrens darter’s seven known populations have been lost. The remaining five populations are small and isolated, making them highly vulnerable to extinction. This decline is primarily due to habitat loss.

The expansion of water-intensive commercial farming and nurseries in the area has contributed to habitat loss by reducing stream flows and degrading water quality, especially during droughts. The Barrens darter is also experiencing hybridization with the invasive fringed darter, which has expanded its range into the Barrens darter’s habitat.

Conservation and Recovery

Efforts to conserve and recover the Barrens darter face significant challenges. The most immediate threat is the limited resilience of the remaining populations and the lack of connectivity between them. Droughts, which are expected to become more severe and prolonged due to climate change, further reduce their already shrinking habitat. The continued spread of the invasive fringed darter poses yet another major threat.

“One of the biggest threats to the Barrens darter is competition and hybridization with the fringed darter,” according to fish and wildlife biologist Abigail Harris. “While the fringed darter is native to the Cumberland River system and likely occurred historically in tributaries to the lower Collins River, they have been expanding their range into the upper reaches of the Collins River system,” Harris says.

So, what’s the prognosis for these struggling little fish? “The Barrens darter is an exemplary species of Tennessee’s natural heritage,” says Harris. “We hope, through various conservation efforts, to support the species and its success so that it can be enjoyed by generations of Tennesseans to come.”

The Barrens darter is listed as endangered by the State of Tennessee, which prohibits taking the species without a permit. The Clean Water Act, enforced primarily by the U.S. Environmental Protection Agency (EPA) and implemented in Tennessee by the Tennessee Department of Environment and Conservation (TDEC), also provides some protection.

Although a federal endangered listing has been proposed and could provide additional protection and resources, the recovery of the Barrens darter depends on sustained efforts to control the fringed darter and restore stream habitats within its limited range.

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