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Ultra-Rare Diamond Darter: Freshwater Species of the Week

  Updated 7/30/12 at 6 pm. This week, the U.S. Fish and Wildlife Service proposed protection of a small fish called the diamond darter (Crystallaria cincotta) under the Endangered Species Act. Also proposed was protection of 122 miles of river as critical habitat for the fish in West Virginia and Kentucky. According to the advocacy group Center...

Diamond, Darter, Crystallaria cincotta
Diamond darters are small, highly endangered fish now found only in a single river in West Virginia. Photo: Conservation Fisheries Inc


Updated 7/30/12 at 6 pm.

This week, the U.S. Fish and Wildlife Service proposed protection of a small fish called the diamond darter (Crystallaria cincotta) under the Endangered Species Act. Also proposed was protection of 122 miles of river as critical habitat for the fish in West Virginia and Kentucky.

According to the advocacy group Center for Biological Diversity, the federal government’s recommendation stems from a legal settlement reached with the group in 2011 to speed protection decisions for species around the country.

The Center for Biological Diversity points out that the diamond darter is extremely rare; fewer than 50 of the fish have been collected over the past 30 years. The small fish has olive-brown diamond shapes on its back and is said to have been named for the sparkling light it reflects during collection at night.

Meagan Racey, a public affairs specialist for the U.S. Fish and Wildlife Service’s Northeast Division, emailed us that: “The diamond darter was listed as a candidate in 2009, and careful assessment of the best scientific and commercial information available regarding the past, present and future threats to the diamond darter pointed us in the direction of listing it as endangered under the ESA. Prior to the multi-district litigation settlement, the Service had already obligated funds and begun working on the scientific proposal to list the darter as endangered. Research and the species’ condition moved this proposal forward.”

freshwater species of the weekAdult diamond darters are around three to five inches long, with the largest individual collected measuring 3.03 inches (7.7 cm). The fish is thought to live two to seven years. It is one of two species in its genus, which also includes the related crystal darterCrystallaria asprella.

Diamond darters bury into the sand of a stream bottom and ambush the insects that serve as their prey. The males set up and protect breeding territories.

The diamond darter was formally described in 2008, based on a few specimens collected going back to 1980. Scientists think it was once found in five states (Ohio, Kentucky, Indiana, Tennessee, and West Virginia), but today is only known in the Elk River of West Virginia, part of the Ohio River Basin. Dams, pollution, and heavy use of the water it depended on wreaked havoc on its populations, in part because the fish needs clean water without too much silt.

Racey added, “The Elk River has the highest diversity of fish and mussels of any watershed in West Virginia, with 100 types of fish and 30 types of freshwater mussels. The diamond darter tends to occur in watersheds like that — with high fish and mussel diversity — and this proposal will help ensure that native variety is there for the future. One way that it does that is through critical habitat, which helps our fellow federal agencies pay special attention to these areas when carrying out, funding or authorizing actions. Proposing critical habitat along with the listing as endangered not only streamlines the process on our end, but it moves our focus toward recovering the diamond darter.

“This is the first proposal for critical habitat in this watershed for any species. It’s also unique because we are proposing not only occupied habitat (28 miles), but unoccupied habitat that is essential for the darter’s conservation and has the suitable features for its future.”

Biologist Tierra Curry of the Center for Biological Diversity said in a statement, “The diamond darter is one of the most endangered fish in the world. We’re thrilled that it’s getting the Endangered Species Act protection that will make sure it isn’t lost forever.”

Curry added that diamond darters are still threatened by mountaintop removal coal mining, oil and gas development, untreated sewage, a fast-spreading invasive toxic algae, and climate change. Still, some protections will now immediately go into effect.

“The Elk River is one of the most ecologically diverse rivers in the country, supporting more than 100 species of fish and 30 species of mussels, but it’s also one of the most threatened. Coal mining occurs throughout the entire Elk River watershed, and fracking is a rapidly emerging threat,” said Curry.

The federal government’s proposed critical habitat is located in Kanawha and Clay Counties in West Virginia, and Edmonson, Hart, and Green Counties in Kentucky.

Before the action is finalized, there is a 60-day public comment period.

The Southeastern Fishes Council had named the diamond darter as one of the “Desperate Dozen” — the 12 most imperiled fish in the southeastern United States. The region is home to more freshwater species than anywhere else, although 50 such species have gone extinct there in recent years.

Vanessa C. Kauffman, a public affairs specialist with the U.S. Fish and Wildlife Service in Arlington, Virginia, told us that in an agreement to settle lawsuits brought by the Center for Biological Diversity and WildEarth Guardians, the agency agreed to work on reviewing the 250 candidate species from the 2010 annual notice of review (including the diamond darter), as well as more than 600 outstanding legal actions. She said the agency has already addressed more than 400 actions.


Brian Clark Howard is an Environment Writer and Editor at National Geographic News. He previously served as an editor for and E/The Environmental Magazine, and has written for,,, Yahoo!, MSN, Miller-McCune and elsewhere. He is the co-author of six books, including Geothermal HVACGreen Lighting and Build Your Own Small Wind Power System.


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