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This paper deals with the study of the surface morphology of barbels, upper lips, and adhesive discs in four hill stream fish species collected from Basistha River, a torrential river in Guwahati city, Assam, India. The four species belonging to the genus Garra namely, Garra gotyla (Gray, 1830), Garra gravelyi (Annandale, 1919), Garra stenorhynchus (Jerdon, 1849), and Garra nasuta (McClelland, 1838) were collected from the same torrential habitat. These fish revealed anatomical peculiarities in their barbels, lips, and adhesive discs which are believed to help them in adapting to such habitats. Organs exhibiting adaptive modifications (barbels, lips, and adhesive discs) were studied with the scanning electron microscope. The study primarily revealed the presence of type I and type II taste buds in the barbels, lips, and adhesive discs, and numerous unculi surrounded by microridges in the upper lips and adhesive discs. A cumulative, intercalated action of these organs enables these fish to adhere and adapt to rocky, torrential streams. Special ability to adapt to these habitats was reflected from the two types of taste buds (I and II) present in the barbels, and the clustering of excrescencies bearing unculi in the lips and adhesive discs of the fish.

This study describes the length-weight and length-length relationships for 28 populations of Garra ruffa in different basins of Iran, including Tigris, Karkheh, Karun, Persis and Hormuz. The length-weight relationships from most localities are reported here for the first time. For most populations the b value was not significantly different from 3, indicating an isometric growth, in a few, it was significantly bigger than 3, indicating a positive allometric growth, and in some, it was significantly smaller than 3, indicating a negative allometric growth. In the whole samples, it was not significantly different from 3, indicating an isometric growth.

High soil erosion and excessive sediment load are serious problems in several Himalayan river basins. To apply mitigation procedures, precise estimation of soil erosion and sediment yield with associated uncertainties are needed. Here, the revised universal soil loss equation (RUSLE) and the sediment delivery ratio (SDR) equations are used to estimate the spatial pattern of soil erosion (SE) and sediment yield (SY) in the Garra River basin, a small Himalayan tributary of the River Ganga. A methodology is proposed for quantifying and propagating uncertainties in SE, SDR and SY estimates. Expressions for uncertainty propagation are derived by first-order uncertainty analysis, making the method viable even for large river basins. The methodology is applied to investigate the relative importance of different RUSLE factors in estimating the magnitude and uncertainties in SE over two distinct morphoclimatic regimes of the Garra River basin, namely the upper mountainous region and the lower alluvial plains. Our results suggest that average SE in the basin is very high (23 ± 4.7 t ha−1 yr−1) with higher values in the upper mountainous region (92 ± 15.2 t ha−1 yr−1) compared to the lower alluvial plains (19.3 ± 4 t ha−1 yr−1). Furthermore, the topographic steepness (LS) and crop practice (CP) factors exhibit higher uncertainties than other RUSLE factors. The annual average SY is estimated at two locations in the basin – Nanak Sagar Dam (NSD) for the period 1962–2008 and Husepur gauging station (HGS) for 1987–2002. The SY at NSD and HGS are estimated to be 6.9 ± 1.2 × 105 t yr−1 and 6.7 ± 1.4 × 106 t yr−1, respectively, and the estimated 90 % interval contains the observed values of 6.4 × 105 t yr−1 and 7.2 × 106 t yr−1, respectively. The study demonstrated the usefulness of the proposed methodology for quantifying uncertainty in SE and SY estimates at ungauged basins.

Among Tashan cave barb Garra tashanensis inhabiting a small cave in southwest Iran, two mental disc (sucking mouth disc) forms were observed. To assess their phylogenetic relationships, disc-less and disc-bearing individuals were analyzed using mitochondrial cytochrome oxidase subunit I (COI) partial DNA sequences. Both mental disc forms nested within one clade with absolute bootstrap support (BS = 100), and the genetic distances between the disc-bearing and disc-less individuals (0.3–0.8%) were considerably lower than inter-species mtDNA sequence distances reported among members of the genus Garra; further, most species delimitation algorithms used here showed disc-bearing and disc-less Tashan cave barbs to be members of a single taxonomic unit. Hence, the observed mental disc variation was not inferred to be a taxonomic feature or a consequence of character displacement. Instead, it was inferred to be a case of character release to diversify among ecological niches in the limited subterranean habitat or a case of relaxed selection, which should be clarified in detail in follow-up ecological and population genetic studies.

Summary Length–weight relationships (LWRs) for one percoid (Johnius coitor) and three cyprinid (Garra birostris, Garra annandalei and Raiamas bola) fish species from the Brahmaputra River basin in Assam, Northeast India, was studied on a monthly basis from November 2015 to December 2016, using fishing gears namely, cast nets (9′, 1/2″) and gillnets (30 × 0.9 m). No previous record is available on LWR data for three of these species.

Northeast India is a hub to several endemic freshwater fish species, yet studies on cytogenetic characterization of most of these fishes remain inadequate. In the present study, three cyprinid fishes, Garra annandalai, Garra gotyla and Pethia shalynius, were collected from streams associated to the Brahmaputra drainage in northeast India. The diploid chromosomal count was obtained as 50, 50 and 52, with a karyotype formula of 14 m + 12sm + 12st + 12t, 12 m + 8sm + 8st + 22t and 12 m + 22sm + 6st + 12t, and fundamental number 76, 70 and 86, respectively, of G. annandalei, G. gotyla and P. shalynius. Cytogenetic profiling of G. annandalai and P. shalynius is a first report in the present study, which will additionally supplement toward correct identification, study genetic inheritance and genome organization of these species.

The practise of restocking and stock improvement as a means of managing fisheries and aquaculture has been widely used. However, it is difficult to claim that fish stocking is effective due to a number of challenges. One of those is the lack of suitable monitoring and assessment methods, although all assessment approaches have their strengths and weaknesses. If the full benefits of fisheries and their long-term sustainability are to be realised, it is necessary to examine the effectiveness of restocking and stock enhancement. Therefore, effective, rapid, and dependable monitoring techniques are necessary. In this study, we used an eDNA-based method to identify G. cambodgiensis at 14 sites throughout Thailand's restocking and stock enhancement programme. eDNA from this species was identified in water samples using quantitative polymerase chain reaction (qPCR) tests with primers and a probe specific to G. cambodgiensis . A successful stocking would show positive eDNA results in water samples collected from the studied sites. Only five of the studied sites returned positive eDNA readings, which could be considered a successful stocking. The locations that contained G. cambodgiensis eDNA were either confirmed to be natural habitats or were regularly stocked with a large number of hatchery fish. In this study, we demonstrated that eDNA is a reliable, fast and accurate alternative method for measuring stock improvement.

We report the first finding of the stygobiotic form of the cyprinid fish Garra rufa (Heckel, 1843), discovered in a single locality in southwestern Iran, while the epigean form of the species is widely distributed in western Asia (Iran, Jordan, Lebanon, Turkey, and Syria). We also report a new locality for its hypogean congener, Garra tashanensis , about 5 km east of its type locality. The two species occur in syntopy in outflows of the Tang-e-Ban, a seasonal karstic spring that only has flowing water during winter and spring, when fish individuals are washed from the cave to the surface. Identification of the investigated samples was confirmed by morphological analyses, COI distances, and a phylogenetic tree. These findings suggest the existence of a large karst aquifer in the Tashan area that harbours several cave species of fish, crustaceans, and gastropods and may have considerable conservation implications.

Since osteological structures of fishes provide important biological and ecological information, studying these structures is valuable. On the other hand, due to lack of data on the osteology of stone lappers, the present study was conducted to provide detailed descriptive osteology of Garra rossica from Mashkid basin, southeastern Iran, comparing it with those of G. typhlops from the Bagh-e Loveh cave, Iran, G. rossica from Nahang River, Mashkid Basin, and G. persica from Zahak River, Sistan basin. For this purpose, 15 specimens of G. rossica were captured from Ladiz River, Mashkid Basin, using an electrofishing device, and fixed in 10% buffered formalin. Then, the specimens were cleared and stained with alcian blue and alizarin red for osteological investigations. A detailed description of the osteological features of G. rossica was provided. Based on the results, several differences were observed between the four species. G. rossica can be distinguished from G. typhlops, G. persica, and G. rossica based on the shape of suspensorium and opercular series, pharyngobranchial bones, ventral and pectoral girdles, caudal, dorsal, and anal fins skeleton, and shape and number of infraorbital elements.

Garra motuoensis, an endemic labeonine fish, was reported distributed in the lower Yarlung Tsangpo River drainage with little published biological information. Herein, we sequenced and characterized the complete mitochondrial genome of G. motuoensis, which was 16,806 bp in length, containing 13 PCGs, 22 tRNA genes, two rRNA genes, one light strand replication origin (O L ), one control region (D-loop), and one replication region. Phylogenetic analysis based on 13 PCGs sequences revealed that G. motuoensis had a closest relationship with G. qiaojiensis. Then, both species clustered with other species of Garra, and next grouped with other genera of subfamily Labeoninae.