The juil ciego or blindwhiskered catfish (''Rhamdia reddelli'') is a species of

three-barbeled catfish The Heptapteridae, or three-barbeled catfishes, are a family of catfish that originate from the Americas. Most species are restricted to South America, but '' Imparfinis lineatus'', '' Nemuroglanis panamensis'' and '' Pimelodella chagresi'' are ...

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. This species is

troglobitic A troglobite (or, formally, troglobiont) is an animal species, or population of a species, strictly bound to underground habitats, such as caves. These are separate from species that mainly live in above-ground habitats but are also able to live u ...

, inhabiting a certain stream that flows through a single cave system.

Description

Like other fish found exclusively in caves, the skin of ''R. reddelli'' lacks pigment. The fish also lacks eyes, instead having various sensory organs for taste, smell, and touch; these can help it to orient itself in the total darkness and locate food. It is a small fish up to long, with a flattened head, a long dorsal fin, and a deeply forked tail. The three barbels on the chin are long and packed with sensory cells.

Distribution

''R. reddelli'' is known from a single cave system in Mexico through which flows an underground stream about long. The cave is near San Antonio Cañada, in the

Sierra Madre de Oaxaca The Sierra Madre de Oaxaca is a mountain range in southern Mexico. It is primarily in the state of Oaxaca, and extends north into the states of Puebla and Veracruz. Geography The mountain range begins at Pico de Orizaba, and extends in a southeas ...

southeast of

Mexico City Mexico City ( es, link=no, Ciudad de México, ; abbr.: CDMX; Nahuatl: ''Altepetl Mexico'') is the capital and largest city of Mexico, and the most populous city in North America. One of the world's alpha cities, it is located in the Valley o ...

Ecology

No living plants are present in this cave, so this fish is mostly reliant on the

detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commun ...

of organic material washed into the cave from the surface. Another source of nutrition is

bat Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most bi ...

guano Guano (Spanish from qu, wanu) is the accumulated excrement of seabirds or bats. As a manure, guano is a highly effective fertilizer due to the high content of nitrogen, phosphate, and potassium, all key nutrients essential for plant growth. G ...

, and the remains of dead bats that happen to fall into the water. With this limited and erratic food supply, the fish has a low metabolic rate and stores fat in its tissues. Breeding only takes place in times of food sufficiency, with a small number of eggs being produced at one time, and in some years, the fish may not breed at all. It exhibits parental care by keeping its newly hatched young in its mouth to prevent

predation Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...

Status

Living in a single cave system, this fish is vulnerable to such events as pollution of the spring and stream that flow through the cave; this puts it in a precarious position as the whole population could be wiped out by a single adverse event. The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

has rated its conservation status as being " critically endangered".

References

* {{Taxonbar, from=Q3278604 Cave fish Endemic fish of Mexico Freshwater fish of Central America Heptapteridae Fish described in 1984 Taxonomy articles created by Polbot Fauna of the Sierra Madre de Oaxaca Papaloapan River