The Borax Lake chub Gila boraxobius is a rare cyprinid

Cyprinid

The family Cyprinidae, from the Ancient Greek kyprînos , consists of the carps, the true minnows, and their relatives . Commonly called the carp family or the minnow family, its members are also known as cyprinids...

 fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 found only in outflows and pools around Borax Lake

Borax Lake (Oregon)

Borax Lake is a small alkali lake in the arid Pueblo Valley of southeastern Oregon, United States near Fields, Oregon. The lake is fed by an underground geothermal well with a temperature of around 190°C. The lake contains high concentrations of sodium borate and arsenic, the latter fatal to...

, a small lake of the Alvord basin, Harney County, Oregon

Harney County, Oregon

-National protected areas:*Malheur National Forest *Malheur National Wildlife Refuge*Ochoco National Forest -Demographics:As of the census of 2000, there were 7,609 people, 3,036 households, and 2,094 families residing in the county. The population density was 1 people per square mile...

.

This species is a dwarf form of Gila, typically reaching only 5 cm in length, although some are as long as 11 cm. The back is generally a dark olive green, while the sides are silvery, with a dark line extending from gill cover to tail, and a scattering of dark melanophores. The fins are colorless, with more melanophores on the rays of the dorsal fin and tail, as well as on the first four rays of the pectoral fins. Similar in many ways to the Alvord chub

Alvord chub

The Alvord chub Gila alvordensis is a rare cyprinid fish endemic to the Alvord basin in southeastern Oregon and northwestern Nevada, USA, known only from a few springs, streams, and marshes in the Sheldon National Wildlife Refuge, and one location elsewhere.The Alvord chub is a small fish, with...

, the Borax Lake species has a longer, wider, and deeper head, and larger eyes, and the caudal peduncle is more slender.

The Borax Lake chub eats a variety of foods, including midge

Midge (insect)

Midges comprise many kinds of very small two-winged flies found world-wide. The term does not encapsulate a well-defined taxonomic group, but includes animals in several families of Nematoceran Diptera. While some midges are vectors for disease, many others play useful roles as prey items for...

 larvae, diatom

Diatom

Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons , fans , zigzags , or stellate colonies . Diatoms are producers within the food chain...

s, copepod

Copepod

Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...

s, ostracod

Ostracod

Ostracoda is a class of the Crustacea, sometimes known as the seed shrimp because of their appearance. Some 65,000 species have been identified, grouped into several orders....

s, and terrestrial insects. Its preferred mode of feeding is to root around in the bottom, but it will go after floating material or feed from the surface if necessary.

This species is the sole fish inhabiting the Borax Lake waters. While parts of the lake itself can, at times, rise about 100 °F (38°C) (being fed from thermal springs), the average temperature ranges between 61 °F - 95 °F (16-35°C). The fish avoid the really warm water, favoring lake's outflows. Its continued existence is threatened by geothermal energy development near the lake, which has already dried up part of the chub's habitat.