Comprehensive comparative morphological analysis of loaches from the subfamily Nemacheilinae is conducted. Forty significant phylogenetic characters are suggested, and phylogenetic relationships are reconstructed. The subfamily Nemacheilinae is subdivided into five tribes (Vaillantellini, Lefuini nov., Yunnanilini nov., Triplophysini nov., and Nemacheilini), and the relationships between these tribes can be expressed by the following formula: Vaillantellini (Lefuini (Yunnanilini (Triplophysini + Nemacheilini))). The classification of highland Asian loaches (Triplophysini) is specified, and the revised diagnoses of the genera from this tribe are given. Heterogeneity of the genus Triplophysa is demonstrated. This genus can be divided into several subgenera, and three new subgenera (Labiatophysa subgen. nov., Indotriplophysa subgen. nov., and Tarimichthys subgen. nov.) are described. A new species Hedinichthys grummorum sp. n is described from the Turpan Depression (northwest China).

Phylogenetic relationships and classification of nemacheiline loaches belonging to the line with lost preethmoideum I are investigated. With consideration of the analysis of 29 apomorphous states of 23 characters, the following hypothesis of relationships within this line is suggested: Oxynoemacheilus + Indoreonectes + Dzihunia + (Seminemacheilus (Afronemacheilus + Nun)) + Iskandaria (Paracobitis + Troglocobitis) + Metaschistura + Paraschistura + (Schistura gr. B (Acanthocobitis + Nemacheilus s. str. + Schistura gr. A)))). Revision of the generic classification of loaches of this line inhabiting water bodies from the Near East and Ethiopia to middle Asia and the Indus upper reaches is made. Key to genera of this region is suggested. Four new genera are described: Afronemacheilus Golubtsov and Prok., g. n. (type species A. abyssinicus), Iskandaria Prok., g. n. (type species I. kuschakewitschi), Metaschistura Prok., g. n. (type species M. cristata), and Paraschistura Prok., g. n. (type species P. sargadensis). Independence of the genera Oxynoemacheilus and Troglocobitis is confirmed. The Oriental Schistura are subdivided into two groups (A and B). Schistura gr. A form a monophyletic line with the genera Acanthocobitis and Nemacheilus s. str. It is noted that the south-China genus Homatula cannot be related to Paracobitis or Schistura as it has no ventral axillar lobe, but it may turn out to be identical to the genus Oreias from the same region.

Gobioid fishes collected in Nha Trang and Van Phong bays (Vietnam) represented by 44 species, including 30 species continuously associated with soft bottoms in the open parts of the bays with normal marine conditions are reviewed. A new species, Navigobius khanhoa sp. n., is described. This species differs from other species of the genus in much higher number of rays in the second dorsal fin (26), smaller size of the mouth, teeth on the jaws arranged in a single row, and other characters. Four species from the genera Acentrogobius, Eviota, Favonigobius, and Gnatholepis have not been identified to the species, and, most likely, some of them are new for science. Nine species are recorded in the fauna of Vietnam for the first time: Aulopareia unicolor, Bathygobius hongkongensis, Egglestonichthys bombylios, Glossogobius circumspectus, Oplopomops diacanthus, Oxyurichthys auchenolepis, Tomiyamichthys ex gr. russus, Tryssogobius porosus, and Valenciennea immaculata. An occurrence of Glossogobius olivaceus in the fauna of Vietnam is confirmed. Three species, G. olivaceus, Oligolepis acutipennis, and Periophthalmus kalolo, are recorded in the Cai River delta for the first time. A new synonymy is established: Eviota gurjanovae (Prokofiev, 2007) = E. prasina (Klunzinger, 1871). The current state of knowledge of Gobiidae fauna of Vietnam is discussed, and the updating of the species composition of Gobiodontini of Nha Trang Bay is presented in addition to the species list published earlier (Prokofiev, 2007).

This study provides a revision of myctophiform fishes (families Neoscopelidae and Myctophidae) from Paleocene, Eocene, and Oligocene deposits of Russia and adjacent regions of the Thetys and Parathetys basins. Diagnoses of the order Myctophiformes and suborders, families, and subfamilies of the suborder Myctophoidei are given. Four genera and four species of myctophiform fishes found in this territory are described in detail: Neocassandra mica, Beckerophotus gracilis (Neoscopelidae), Eomyctophum koraense, and Oligophus moravicus (Myctophidae). Nominal species Eomyctophum menneri Dan., 1947 and E. limicola Dan., 1960 are referred to synonyms, respectively, to E. koraense and O. moravicus. O. moravicus may be represented in the lower Oligocene of the Caucasus by more than one species, so that specimens in better condition are necessary to describe them. The ranks of the families Sardinioididae and Neocassandridae were reduced to subfamilies within Neoscopelidae. The genus Eomyctophum was separated into the subfamily Eomyctophinae, differing from other myctophiform fishes by the absence of lenslike thickenings of the photophores. The classification and the origin of Myctophiformes are discussed, phylogenetic interrelationships within the order Myctophoidei are considered, a brief review of fossil myctophiforms is presented, and the history of their study is given.

The only known fossil representative of the genus Triplophysa, T. opinata from the middle-upper Miocene of Kirgizia is redescribed. It is suggested that this species is closest to the species groups “dorsalis” and “labiata” (sensu Prokofiev, 2002, 2004a). The fossil finding clearly suggests that Triplophysa developed no later than in the middle of the Neogene.

Black swallowers are revised (the genus Chiasmodon Johns.), and two species (C. niger Johns. and C. lavenbergi Prok.) are recognized as valid in this genus. The nominal taxa Ponerodon vastator Alcock, C. subniger Garman, C. braueri Weber, C. bolangeri Osório, C. microcephalus Norman, and C. n. pluriradiatus Parr are reduced to synonyms of C. niger. Individual, ontogenetic, and geographic variation of C. niger is studied. From the latter, the morphotype is separated and characterized by comparatively more developed dentition of gill arches, which is designated as C. cf. niger. Its relationships with the nominal taxa described earlier are not quite clear. It is known from few specimens from localities remote from each other with the area of C. niger. Taking into consideration the absence of transitional forms, the differences of armament of gill arches may have taxonomic significance. However, it cannot be excluded that C. cf. niger may be an extreme variant of variation of this species by the aforementioned character. C. lavenbergi differs from C. niger in the retention of dermal spinules in adults and in fixed marginal teeth in jaws. Detailed morphological descriptions of aforementioned species and forms are presented, as well as the key and information on their distribution and the map of areas. Morphological and ecological characteristics of black swallowers of the genus Chiasmodon are compared with those in other genera of this family.