Garra

Freyhof, JÖrg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, De Gruyter : 176

Garra

The genus Garra comprises small fishes widely distributed in West South and Southeast Asia, and tropical Africa. The genus is highly diverse, with approximately 190 species currently recognised, while many others await formal description. It is the most speciose genus of Cyprinids in West Asia, with 42 species. The diversity of Garra in West Asia has long been significantly underestimated, as several species exhibit highly similar meristic character states and even the complex gular discs behind the mouth exhibit minimal consistent interspecific variation. Recent molecular studies have greatly contributed to the understanding of the diversity of this genus.

Most Garra species can be readily distinguished from other cyprinids by a prominent, uniquely shaped gular disc on the skin behind the lower jaw. This gular disc is structured into an anteromedian fold and a central callus. Garra species are often adapted to swift-flowing mountain streams, where they are aided in maintaining their position in the current by the gular disc and the lateral position of their large, paired fins. Furthermore, the air bladder is often reduced to reduce buoyancy. Rheophilic, current-loving species usually have a very large gular disc, but the gular disc can be reduced or even absent in some species that do not reside in fast currents.

The presence of a gular disc has long been regarded as the most important diagnostic character for Garra . Recent phylogenetic studies suggested that its presence is a plesiomorphic condition (an ancestral character state) in a range of labeonine cyprinids. This is evidenced by the fact that several labeonine lineages that lack the gular disc are nested within lineages that have a gular disc. Historically, species without a gular disc have been excluded from Garra . In West Asia, such species were previously placed in Hemigrammocapoeta and Iranocypris , but looking more closely, all of these still have remnants of some elements of the gular disc. It has long been suggested that they are closely related to Garra , and the “absence” of the gular disc is a secondary, adaptive character state in these fishes. This was recently supported by molecular data, which indicated that Hemigrammocapoeta species do not form a monophyletic lineage, but the species are related to three different groups of Garra species. All former Hemigrammocapoeta , Iranocypris , Tylognathus , and Typhlogarra from West Asia are included here within the genus Garra .

All Garra species feed on periphyton, plants, and detritus but are opportunistic feeders when other food sources are readily available. In streams where Garra are common, they have a substantial effect on the stream ecosystem by permanently grazing almost all surfaces. In West Asia, most species of Garra are ubiquitous inhabitants of streams and rivers. Still, they also occur in springs, lakes with stony shores, and even in marshes with dense vegetation. In southern Iran and the Arabian Peninsula, Garra are typically found in isolated pools in wadis that are otherwise dry, except when rain floods the river courses. They also occur in subterranean habitats.

Many species of Garra display prominent tubercles on the snout. The function of these tubercles has been discussed extensively, and it is generally believed that they function in territoriality and social interaction. In several species of Garra , the outer tubercles on the snout are enlarged and serve a social function. In most species, only some individuals develop prominent tubercles, and this character state is not associated with the sex of individuals. It has been proposed that individuals holding a territory develop tubercles, and those without territory do not. It has also been suggested that the snout tubercles may reduce the impact of rushing waters. However, these hypotheses remain untested. Further reading. Menon 1964 (diversity and biogeography); Krupp 1985d (phylogenetic position of Hemigrammocapoeta ); Stiassny & Getahun 2007 (diversity in Africa); Yang et al. 2012 (phylogeny of Labeonines); Hamidan et al. 2014 ( Iranocypris ); Behrens-Chapuis et al. 2015 (molecular phylogeny); Esmaeili et al. 2016c; Zamani-Faradonbe et al. 2021b ( Iran); Hashemzadeh Segherloo et al. 2016a (convergent reduction of gular disc; phylogeny).

Garra mamshuqa ; Wadi al-Khun, Yemen; 52 mm SL. © F. Krupp. Garra amirhosseini ; Sartang-e-Bijar hot spring, Iran; 49 mm SL.