Achondrostoma  (Achondrostoma arcasii)

Achondrostoma arcasii is classified as Vulnerable (VU) on the IUCN Red List (1).

A freshwater fish of Portugal and Spain, Achondrostoma arcasii is a little known species threatened by the loss of its habitat. It can be distinguished from related species by having four or five rows of scales between the lateral line and the pelvic fins, as well as a rounded snout, with an enlarged, horny lower lip, and particularly large eyes (2) (3).

Achondrostoma arcasii is found in Portugal and Spain, where it occurs in most rivers north of Jucar and Tagus, including rivers around the Atlantic drainage. It has been introduced to the Guadiana drainage (1) (2).

Achondrostoma arcasii inhabits the middle reaches of freshwater rivers, as well as lakes, mountain streams and reservoirs in hilly areas (1).

Achondrostoma arcasii is a poorly-studied species, and there is very little known about its biology and behaviour. However, it is thought to be a short-lived species with a fairly opportunistic diet, eating a variety of aquatic invertebrates (2).

Like other members of the Cyprinidae family, Achondrostoma arcasii lacks teeth, instead possessing a pair of enlarged bones in the throat, which have structures known as ‘pharyngeal teeth’ that are used to process food (4).

Achondrostoma arcasii is threatened by the loss and degradation of its habitat, and its population is thought to be in decline. Canal construction, water pollution, dam construction and introduced species have all be identified as threats to this species (1) (2).

Although Achondrostoma arcasii has not been the target of any specific conservation measures, it is listed on Annex II of the European Union Habitats Directive and on Appendix III of the Bern Convention, which aims to conserve wild flora and fauna and their natural habitats (1) (5) (6).

Find out more about Achondrostoma arcasii:

• FishBase - Achondrostoma arcasii:
  http://www.fishbase.us/Country/CountrySpeciesSummary.php?c_code=620&id=23608