Nemacheilidae, Regan, 1911

Freyhof, JÖrg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, De Gruyter : 468-470

Family Nemacheilidae

Stone loaches

A large family with 49 genera and more than 840 known species (more than 2000 may exist) from the rivers of Asia, Europe, and Ethiopia. Nemacheilid loaches are the second largest family of cypriniform fishes and the least known large group within freshwaters in Asia. Actually, 112 known species of nemacheilid loaches are recognised in West Asia. However, further species will be discovered in the future. Stone loaches are occasionally confused with spined loaches of the family Cobitidae , which also possess three pairs of barbels. In contrast to stone loaches, spined loaches have an erectable suborbital spine that they use for defense. Such a spine is absent in stone loaches; both families have very different general appearances. In many Oxynoemacheilus and Paraschistura species, males exhibit an exposed lachrymal bone called a suborbital flap or groove. In contrast, other species lack this character. The shape of this structure can be used for identification purposes. There have been speculations that the suborbital flap or groove exposure is a seasonal character. However, this still needs to be demonstrated, and further research is required.

The generic structure of nemacheilid loaches from West Asia has been confused for a long time. Species have been placed in Nemacheilus (an East Asian genus), Barbatula (a European and North Asian genus), Orthrias (a synonym of Barbatula ), Nun (a synonym of Oxynoemacheilus ), Ilamnemacheilus (a synonym of Oxynoemacheilus ), and Metaschistura (a synonym of Paraschistura ). Molecular studies have demonstrated that eight genera can be recognised in West Asia, with Oxynoemacheilus being the most speciose and widespread. However, the situation still needs to be fully settled, as Seminemacheilus turns out to be nested within Oxynoemacheilus in some phylogenetic analyses, while in others, it represents its own genus. Indeed, both genera are similar in many characters and poorly distinguished. Triplophysa stoliczkai has been recorded from the Sistan basin in Iran, subsequently identified as Paraschistura alta .

Open Access. © 2025 JÖrg Freyhof, Baran Yoğurtçuoğlu, Arash Jouladeh-Roudbar and Cüneyt Kaya, published by De Gruyter. the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

https://doi.org/10.1515/9783111677811-021

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Nemacheilid loaches inhabit a wide range of water bodies, typically found in swift-flowing water, where they feed on small invertebrates. Up to five nemacheilid species and up to three species of Oxynoemacheilus have been found in syntopy, making identifying species in the field challenging. Syntopic species are usually found in different microhabitats, often in different current velocities. However, the ecological niche separation in different loaches has yet to be studied. All species appear to spawn for the first time at 1 year; most individuals seem to be multiple spawners but spawn only one to two seasons. Biological details are unknown for almost all species. Further reading. Tang et al. 2006 (phylogeny); Šlechtová et al. 2007 (phylogeny); Prokofiev 2009 (genera); Freyhof et al. 2011 (diversity); Kottelat 2012 (diversity); Jouladeh-Roudbar et al. 2015c ( Paraschistura alta record from Iran); Hashemzadeh Segherloo et al. 2016b (West Asian genera).

6a - Colour pattern on flank with regularly- or irregularly set bars, often dissociated into irregularly shaped blotches, especially on flank in front of dorsal origin; most species with prominent black spot at base of unbranched dorsal rays and on first and sometimes second branched rays; a dark-brown or black bar or 1–2 black blotches at caudal base; no whitish or yellowish triangular patch on posteriormost upper and lower caudal peduncle; caudal deeply emarginate or forked.

……………… Paraschistura + Schistura

6b - Colour pattern on flank with a marbled or mottled pattern, usually with a dark-brown or grey irregularly shaped, midlateral stripe, often restricted to caudal peduncle; no prominent black spot at base of unbranched dorsal rays or on first or second branched rays; no dark-brown or black bar or blotch at caudal base; a prominent whitish or yellowish triangular patch on posteriormost upper and lower caudal peduncle; caudal slightly emarginate.

……………… Sasanidus