Schizothorax Species Research Articles

Exploitation of Key Regulatory Modules and Genes for High-Salt Adaptation in Schizothoracine by Weighted Gene Co-Expression Network Analysis

Schizothoracine fishes in saltwater lakes of the Tibetan Plateau are important models for studying the evolution and uplift of the Tibetan Plateau. Examining their adaptation to the high-salt environment is interesting. In this study, we first assembled the RNA-Seq data of each tissue of G. przewalskii, G. selincuoensis, and G. namensis from Qinghai Lake, Selincuo Lake, and Namtso Lake, respectively, obtained by the group previously. After obtaining reliable results, the adaptation of the gills, kidneys, and livers of the three species to the high-salinity environment was assessed by weighted gene co-expression network analysis (WGCNA). Using module eigengenes (ME), 21, 22, and 22 gene modules were identified for G. przewalskii, G. selincuoensis, and G. nemesis, respectively. Functional clustering analysis of genes in the significant association module identified several genes associated with osmolarity-regulated potential KEGG pathways in the gills of three species of Schizothoracine fish. Th17 cell differentiation pathway was up-regulated in the gills of all three species; histocompatibility class 2 II antigen and E alpha (h2-ea) were up-regulated genes in this pathway. Functional clustering analysis of genes in apparently related modules in the kidney unveiled several differential KEGG pathways. The pentose phosphate pathway was up-regulated in the three Schizothoracine fishes, and glucose-6-phosphate dehydrogenase (g6pd) was an up-regulated gene in this pathway. In the livers of the three Schizothorax species, the propanoate metabolism pathway was up-regulated, and succinate-CoA ligase GDP-forming subunit beta (suclg2) was an up-regulated gene in this pathway. The above analyses provide reference data for the adaptation of Schizothorax to high-salt environments and lay the foundation for future studies on the adaptive mechanism of Schizothorax in the plateau. These results partly fill the void in the knowledge gap in the survival adaptations of Schizothoracine fishes to highland saline lakes.

A Comparative Study on Growth Rates and Length-weight Relationships of Snow Trout (Schizothorax sp.) from Rasuwa, Nuwakot, and Okhaldhunga Districts of Nepal

Aims: Snow trout (Schizothorax spp.) are vital to Nepal's aquatic biodiversity and economy, yet little research has addressed their growth potential under controlled conditions. This study aimed to evaluate the growth performance of snow trout from three regions of Nepal (Okhaldhunga, Nuwakot, and Rasuwa) in captivity. Study Design: Original Research Article. Place and Duration of Study: Fisheries Research Station (FRS), Trishuli Nepal, between August 18 November 24, 2023. Methodology: Schizothorax species were collected from Okhaldhunga, Nuwakot, and Rasuwa districts and acclimated to the environment of the FRS in three separate raceways prior to the feeding trial. From each location, a population of 450 apparently healthy and uniform sized snow trout (initial weight: 20.00 + 1.2g) were then distributed into 3 raceway tanks, altogether 9 raceways for 3 groups, feeding upon the commercial feed (48% crude protein) in the form of dough at 3% of the body weight for 90 days. At the end of the feeding trial, growth parameters, including weight gain, specific growth rate (SGR), condition factor (K) and Length-weight relationship (LWR) were measured. Survival rate and water quality parameters were also measured. Statistical analysis for group’s means differences was conducted using one-way ANOVA in R Studio for Windows at a 5% level of significance. Results: Results indicated Fish from Nuwakot exhibited the highest weight gain (3.61 ± 1.82 g) and SGR (0.23 ± 0.12% per day), though these differences were not statistically significant (P >0.05). The condition factor (K) was highest for Rasuwa fish (0.98), followed by Nuwakot (0.97) and Okhaldhunga (0.97) (P >0.05), indicating that the fish were relatively thin, possibly due to poor nutrition or stressful conditions. The LWR analysis revealed high length-weight correlations for all groups, with Rasuwa fish exhibiting a positive allometric growth pattern (b=3.02), whereas Okhaldhunga (b=2.93) and Nuwakot (b=2.94) fish showed negative allometric growth patterns. This may suggest that snow trotu from Rasuwa were in relatively good physiological condition and adapting well to the rearing conditions at the FRS. Although with no statistical difference, the survival rate was highest for fish from Nuwakot (86.67%), followed by Rasuwa (80.00%) and Okhaldhunga (77.33%) (P >0.05). This may indicate the adequacy of the water quality (average temperature 11.75 ± 0.42℃, dissolved oxygen more than 7 mg/L, and pH 7.71 ± 0.16) maintained during the study. Conclusion: The findings suggest that while the snow trout demonstrated the ability to survive yet grow slowly under captivity, their growth performance may be significantly enhanced by optimizing rearing conditions, particularly slightly higher water temperature. This study underscores the need for targeted improvements in aquaculture practices to support the effective domestication and conservation of snow trout in Nepal.

Observation on embryonic development of Gymnodiptychus dybowskii (Kessler, 1874) in Manas River, Xinjiang, China

To protect the germplasm resources of Gymnodiptychus dybowskii (Kessler, 1874), a species endemic to Xinjiang, the key stages of embryonic development of G. dybowskii were studied. From May to July 2021, the artificial breeding of G. dybowskii was carried out at the fish breeding station of the Kenswart Water Conservancy Project. The embryos and early larvae were obtained using temperature promotion, water stimulation, hormone induction, and dry insemination techniques. their development process was observed, and morphological characteristics of each developmental stage were recorded. The results showed that the mature oocyte was round, heavy, and light yellow, with an egg diameter of (2.32 ± 0.21) mm. The fertilized egg was slightly viscous, and the viscosity disappeared after water absorption. Under the temperature of 15.6-17.7 ℃ (16.23 ± 0.52) ℃, the embryonic development of G. dybowskii lasted for 142 h and 33 min and went through 7 stages of fertilization, cleavage, blastula, gastrula, neurula embryo, organ formation, and membrane hatching, with a total of 26 periods. The membrane broke after 2376.724 ℃·h. The embryonic development of G. dybowskii follows the rule of freshwater bony fish, but it differs from other Schizothorax species in the muscular effect period and membrane emergence mode. In addition, differences in hatching water temperature among different geographic populations lead to differences in embryo development duration and accumulated temperature, which further proves that G. dybowskii is highly adaptive to the ecological environment of its habitat water, and these characteristics together constitute its survival and reproduction strategy in the natural environment. In this study, through the artificial breeding experiment of G. dybowskii, the characteristics of its embryonic development were explored, which laid the foundation for the cultivation of unique fish seedlings, enriched the early life history data of G. dybowskii, and further provided basic data for its resource protection.

Genomic analysis and phylogenetic characterization of Himalayan snow trout, Schizothorax esocinus based on mitochondrial protein-coding genes.

Mitochondrial DNA (mtDNA) has become a significant tool for exploring genetic diversity and delineating evolutionary links across diverse taxa. Within the group of cold-water fish species that are native to the Indian Himalayan region, Schizothorax esocinus holds particular importance due to its ecological significance and is potentially vulnerable to environmental changes. This research aims to clarify the phylogenetic relationships within the Schizothorax genus by utilizing mitochondrial protein-coding genes. Standard protocols were followed for the isolation of DNA from S. esocinus. For the amplification of mtDNA, overlapping primers were used, and then subsequent sequencing was performed. The genetic features were investigated by the application of bioinformatic approaches. These approaches covered the evaluation of nucleotide composition, codon usage, selective pressure using nonsynonymous substitution /synonymous substitution (Ka/Ks) ratios, and phylogenetic analysis. The study specifically examined the 13 protein-coding genes of Schizothorax species which belongs to the Schizothoracinae subfamily. Nucleotide composition analysis showed a bias towards A + T content, consistent with other cyprinid fish species, suggesting evolutionary conservation. Relative Synonymous Codon Usage highlighted leucine as the most frequent (5.18%) and cysteine as the least frequent (0.78%) codon. The positive AT-skew and the predominantly negative GC-skew indicated the abundance of A and C. Comparative analysis revealed significant conservation of amino acids in multiple genes. The majority of amino acids were hydrophobic rather than polar. The purifying selection was revealed by the genetic distance and Ka/Ks ratios. Phylogenetic study revealed a significant genetic divergence between S. esocinus and other Schizothorax species with interspecific K2P distances ranging from 0.00 to 8.87%, with an average of 5.76%. The present study provides significant contributions to the understanding of mitochondrial genome diversity and genetic evolution mechanisms in Schizothoracinae, hence offering vital insights for the development of conservation initiatives aimed at protecting freshwater fish species.

Length-Weight-Age Relationship of Schizothorax eurystomus Kessler, 1872 and Comparison to Other Snow Trout Species in Central Asia

This study presents a comprehensive analysis of the length-weight relationship, condition factors, and age of Schizothorax eurystomus in the Shakhimardan River basin in Central Asia, along with a comparative perspective to other Schizothorax species in the region. The study found that S. eurystomus exhibits positive allometric growth, which is consistent with similar patterns observed in this species from the Syr Darya River basin. The two analyzed condition factors showed mean values within the normal range, indicating good feeding and environmental conditions. However, significant disparities between minimum and maximum values of these factors indicated varied growth conditions which may be influenced by anthropogenic factors. Age estimation using opercular bones showed variations in the total length among fish of the same age, and a clear age distribution pattern across different sites. Younger fish predominantly inhabited the shallower, warmer, and lower sections of the river, which is impacted by agricultural water diversion, while older specimens were found in areas with higher discharge and deeper pools. Overall, this research provides valuable insights into the life history traits of S. eurystomus, underlining the need for sustainable fishery management and conservation strategies in the Shakhimardan River basin. The findings also emphasize the importance of considering habitat quality and anthropogenic pressures regarding understanding both fish population dynamics and growth patterns.

Characterization of the Complete Mitochondrial Genome of Schizothorax kozlovi (Cypriniformes, Cyprinidae, Schizothorax) and Insights into the Phylogenetic Relationships of Schizothorax.

Schizothorax kozlovi is an endemic and vulnerable fish species found in the upper Yangtze River in China. Over the past few years, the population resources of S. kozlovi have been nearly completely depleted owing to multiple contributing threats. While the complete mitochondrial genomes serve as important molecular markers for phylogenetic and genetic studies, the mitochondrial genome of S. kozlovi has still received little attention. In this study, we analyzed the characterization of the mitochondrial genome of S. kozlovi and investigated the phylogenetic relationships of Schizothorax. The complete mitochondrial genome of S. kozlovi was 16,585 bp in length, which contained thirty-seven genes (thirteen protein-coding genes (PCGs), two ribosomal RNA genes (rRNAs), twenty-two transfer RNA genes (tRNAs)) and two non-coding regions for the origin of light strand (OL) and the control region (CR). There were nine overlapping regions and seventeen intergenic spacers regions in the mitochondrial genome. The genome also showed a bias towards A + T content (55.01%) and had a positive AT-skew (0.08) and a negative GC-skew (-0.20). All the PCGs employed the ATG or GTG as the start codon and TAA, TAG, or single T as the stop codon. Additionally, all of the tRNAs displayed a typical cloverleaf secondary structure, except trnS1 which lacked the D arm. The phylogenetic analysis, based on the maximum likelihood (ML) and Bayesian inference (BI) methods, revealed that the topologies of the phylogenetic tree divided the Schizothorax into four clades and did not support the classification of Schizothorax based on morphology. The phylogenetic status of S. kozlovi was closely related to that of S. chongi. The present study provides valuable genomic information for S. kozlovi and new insights in phylogenetic relationships of Schizothorax. These data could also offer fundamental references and guidelines for the management and conservation of S. kozlovi and other species of Schizothorax.

Mitochondrial genome sequence characteristics and phylogenetic analysis of Schizothorax argentatus

Schizothorax argentatus that only distributes in the Ili River basin in Xinjiang is one of the rare and endangered species of schizothorax in China, thus has high scientific and economic values. In this study, the complete mitochondrial genome sequence of S. argenteus with a length of 16 580 bp was obtained by high-throughput sequencing. The gene compositions and arrangement were similar to those of typical vertebrates. It contained 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and a non-coding region (D-loop). The nucleotide compositions were A (30.25%), G (17.28%), C (27.20%), and T (25.27%), respectively, showing obvious AT bias and anti-G bias. Among the tRNA genes, only tRNA-Ser(GCU) could not form a typical cloverleaf structure due to the lack of dihydrouracil arm. The AT-skew and GC-skew values of the ND6 gene were fluctuating the most, suggesting that the gene may experience different selection and mutation pressures from other genes. The mitochondrial control region of S. argenteus contained three different domains, i.e., termination sequence region (ETAS), central conserved region (CSB-F, CSB-E, CSB-D, and CSB-B), and conserved sequence region (CSB1, CSB2, and CSB3). The conserved sequence fragment TT (AT) nGTG, which was ubiquitous in Cypriniformes, was identified at about 50 bp downstream CSB3. Phylogenetic relationships based on the complete mitochondrial genome sequence of 28 Schizothorax species showed that S. argenteus had differentiated earlier and had a distant relationship with other species, which may be closely related to the geographical location and the hydrological environment where it lives.

Comparative account on the length-weight and length-length relationships and condition factor of six cyprinid fishes from Dal Lake, Kashmir

Fish landings are routinely measured for length and weight to study fish bioecology, which provide important information about biomass, population dynamics and condition of fish. The current study describes the length-weight relationships (LWRs) and length-length relationships (LLRs) of six fish species (Cyprinus carpio, Carassius carassius, Schizothorax niger, S. curvifrons, Crossocheilus diplochilus and Pethia conchonius) based on seasonal fish sampling from the Dal Lake during September 2019 to August 2020. The estimated LWRs and LLRs were highly significant (p < 0.05) with high coefficient of determination r2 and the estimated b values ranged from 2.50 to 3.55. The estimated b values revealed negative allometric growth of fish species except P. conchonius which possesses positive allometric growth. The mean value of condition factor for C. carpio, C. carassius, S. niger, S. curvifrons, C. diplochilus and P. conchonius were 1.43±0.25, 1.55±0.24, 0.86±0.14, 0.80±0.13, 1.21±0.17 and 1.64±0.34 respectively and it varied significantly among these fish species (ANOVA: p < 0.05). The study shows LWRs, LLRs and current condition of some forage fish species viz., C. carassius, C. diplochilus and P. conchonius as well as invasive C. carpio and local Schizothorax species from the Dal Lake, all possessing economic and conservation significance.

Evaluation of seasonal cyclicity of testicular development in adult Himalayan snow trout, Schizothorax plagiostomus

Schizothorax plagiostomus commonly known as snow-trout, is a popular game-food fish, found in the cold waters of the rivers, streams, tributaries and lakes of the Hindukush- Karakoram- Himalayan mountains/ foothills even at the elevation of 1180–3000 m above from the sea level and is considered to the be major source of animal protein. In recent past, there has been a severe decline in Schizothoracine population due to uncontrolled anthropogenic activities and climate change. Therefore, there is an urgent need for critical analysis of annual gonadal development in Schizothorax species. In this study, the seasonal variations of testicular architecture and development were examined in adult S. plagiostomus at Garhwal Himalaya, Uttarakhand, India. Testicular-somatic index were found to be ranged from 0.254 ± 0.06–7.104 ± 1.62 with maximal value recorded in September-October and minimal in April-May. Testicular histology revealed abundance of undifferentiated spermatogonia, meiotic spermatid and spermatozoa in pre-spawning and spawning capable phases respectively. The ultra-structure of spermatozoa showed 1.78 ± 0.27 µm long ovoid shaped head without any acrosome, 0.35 ± 0.05 µm long ellipsoidal mid-piece and 22.5 ± 0.65 µm long flagella. We further have evaluated the milt/semen volume, estimated the sperm density and motility in male brooders. Notably the spermatogenic capacity was found to be consistent in two breeding seasons i.e. spawning capable (September-October) and residual spawning (February-March) phases. In summary, this is the first comprehensive qualitative and quantitative report of the seasonal variations of the spermatogenic output in adult male S. plagiostomus. This data may provide valuable information for the conservation management and artificial breeding program of S. plagiostomus.

Evaluation of water quality and dam for sustaining the fish population dynamics

Bhagirathi is a Himalayan River, which flows in Uttrakashi district in Uttarakhand state. It is one of the most important streams of the Ganga River. This river is famous for dam construction and fisheries development. The fishes of commercial importance in cold water are Mahaseer, Snow Trout. The fish production depends on the physical, chemical as well as biological qualities of water. In the present paper, water quality evaluation and dam in the sustaining fish population dynamics have been reviewed to make aware the fish culturist and environmentalist about the water quality factors which influence health of a pond and to increase the fish yields to meet the growing demands of present time scenario of the our country. The construction of dams causes many problems. Water quality and discharge of water from the dam wall systems also indirectly affect the fish populations. In this study, we also review some of the important impacts associated with dams and their recommended mitigation measures. There is a negative impact on fish population dynamics, especially for downstream habits due to dams. Water quality is measured like temperature, turbidity, carbon dioxide, pH, alkalinity, hardness, BOD, TDS, Turbidity. The maximum oxygen content of water was recorded in January 13.02 ± 0.166 mg l−1 and minimum 9.4 ± 0.05 mg l−1 in July in site I phase I (before the reservoir dam wall). While in site II and phase I (After the dam), the maximum DO was observed in the month of January of 12.1 mg l−1 and minimum in July of 8.93 mg l−1. This is because water level is minimized in site II almost dried in winter. The CO2 of the Maneri Bhali phase I -Site I (before dam) was recorded maximum in April 3.10 ± 0.012 mg l−1. In Maneri Bhali phase I -Site II (After dam), the CO2 was recorded maximum 3.01 ± 0.003 mg l−1 in the month July. The river of Garhwal Himalaya harbors a rich aquatic diversity, the most common endemic fish species that inhabit this fresh water is the Schizothorax species. The maximum no. of fish were observed in winter and minimum in monsoon. At present, the production of these fishes from the streams is very poor and is not well managed from recreational and conservation point of view. If such is developed properly, it can have revenue potential for our state government. Sports, fisheries, tourism should be promoted.

DAM IMPACT ON WATER QUALITY AND MORPHOMETRIC CHARACTERISTIC OF SCHIZOTHORAX SPECIES IN BHAGIRATHI RIVER OF UTTARKASHI, UTTARAKHAND

A study was conducted on the morphometric characteristics of Schizothorax species of fish on samples collected from Bhagirathi river in Uttarkashi district of Uttarakhand state. Samples were taken from the study sites to measure some important parameters of water quality, which greatly influenced the morphological characteristics of the fish. Morphometric features such as total length, pectoral, pelvic, anal, dorsal, head, caudal length of eyes, caudal width and weight were recorded. Significant effects of dam on fish are observed on the morpho-metric of Schizothorax sp. There was no change in the characters but the wall of the dam put the selection pressure. The maximum length, weight of fish was observed in the study area during winter season and minimum during rainy season. The maximum length and weight were found before the dam. Changes in habitat, physico-chemical parameters, less aquatic macro-invertebrates lead to shorter lengths of fishes. Proper management techniques should be required for the production of fish. This paper will provide knowledge of the impact of dam on the morphometric character of fish along with parameters of water quality. It also gives in-depth knowledge of proper management of river fisheries.

Length-weight relationship, growth pattern and condition factor of four indigenous cypriniform Schizothorax species from Vishav Stream of Kashmir Himalaya, India

The indigenous Schizothorax spp. in the valley of Kashmir are facing constant threats and decline in their overall population. The current aim was to analyse the comparative length-weight relationship (LWRs) and condition factor (K) of 350 specimens belonging to four Schizothorax spp. (S. plagiostomus, S. esocinus, S. labiatus and S. curvifrons) from the Vishav Stream of Kashmir Himalaya, India. The fish specimens were sampled for a period of one year from April 2018 to March 2019. The results revealed that the growth coefficient ‘b’ in all the four Schizothorax spp. was found very close to 3, indicating an isometric growth pattern. No significant difference in the ‘b’ values of four Schizothorax spp. was found when compared with the isometric value (t-test: p > 0.05). The mean value of the ‘K’ for S. plagiostomus, S. esocinus, S. curvifrons and for S. labiatus were 0.81 ± 0.07, 0.80 ± 0.08, 0.85 ± 0.08 and 0.88 ± 0.12 respectively. The mean condition factor did not vary across four species (ANOVA: p > 0.05). The present findings could serve as baseline information for the management, stock assessment and future studies of indigenous capture fishery resources of the Vishav Stream and other similar habitats.

Fishway design based on the swimming ability of two Schizothorax species in the Yalung River, China

To investigate the swimming ability of two Schizothorax species in the Yalung River and provide basic parameters for the studies on fish behavior and the design of fish passage, we exa-mined the induced velocity, critical swimming speed, and burst swimming speed in Schizothorax dolichonema and Schizothorax prenanti with incremental velocity method and the durable swimming speed in S. dolichonema with fixed velocity method. The results showed that the induced velocity of both species increased first and then plateaued with the increases of body length, with the maximum values being lower than 0.2 m·s-1. The critical swimming speed and burst swimming speed of S. dolichonema were (0.81±0.20) and (1.49±0.26) m·s-1, respectively, while the relative critical swimming speed and the relative burst swimming speed were (4.90±1.73) and (9.77±1.72) BL·s-1 (BL: body length), respectively. For S. prenanti, the critical swimming speed and burst swimming speed were (0.73±0.24) and (1.17±0.39) m·s-1, respectively, while the relative critical swimming speed was (6.88±2.82) BL·s-1, and the relative burst swimming speed was (11.75±2.77) BL·s-1. The swimming duration of S. dolichonema was negatively correlated with the flow velocity of 0.7-1.5 m·s-1, and the relationship between fatigue time (T) and flow velocity (V) was fitted into lgT=-2.52V+5.59. The relationship between expected fishway length (d) and the tolerable maximum average flow velocity (Vf max) was accordingly derived to be Vf max=-0.17lnd+1.74. Taken together, the fishway targeting S. dolichonema and S. prenanti was recommended to generate the in-channel velocity larger than 0.2 m·s-1, while the velocity at the entrance and verticle slot should be 0.73-1.67 m·s-1, and the main-flow velocity in rest pools should be 0.2-0.7 m·s-1.

Phylogenetic association of Cyprinid (Schizothorax) inferred from complete mitochondrial genome

Whole mitochondrial DNA (mtDNA) of S.esocinusand S. plagiostomus was found to be 16,591 and 16,564 bp respectively with 13 protein-coding genes, 2 rRNAs genes, 22 tRNA genes and 2 non-coding region. For valuing the phylogenetic relationship of a species on the basis of whole mitogenome are considered to be a great importance. In this study, we sequenced whole mitogenome of S.esocinusand S. plagiostomus and compared with the whole mitogenome sequences of members of other families (Balitoridae, Nemanchillidae and Cobatidae). The monophyly of the family Cyprinidae and a clade comprising Balitoridae and Nemanchillidae while Cobatidae with paraphyletic origin was strongly supported by the resultant phylogenies, recognized that Cyprinidae was closely related with the family Cobatidae than other ones. The results indicated that whole mitochondrial genome has a great importance in studying variation in genes and phylogenetic relationship in the subfamily Schizothoracinae. This data offering the molecular phylogenetic frame work of important Schizothorax species found in Swat.

Better Resolution for Cytochrome b than Cytochrome c Oxidase Subunit I to Identify Schizothorax Species (Teleostei: Cyprinidae) from the Tibetan Plateau and Its Adjacent Area.

The genus Schizothorax is one of the most diverse groups of schizothoracine fish. Many species within this genus possess highly similar morphological characters and are very difficult to be identified accurately only based on morphology. The present study aims to test the effectiveness of mitochondrial cytochrome c oxidase subunit I (COI) gene and cytochrome b (Cytb) gene for discriminating the Schizothorax fish. A total of 185 individuals of 11 species for COI gene and 264 individuals of 23 species for Cytb gene were used for analyzing, respectively. According to the genetic distances, only one species based on COI gene and five species based on Cytb gene had "barcoding gaps," respectively. The tree-based analysis displayed that four species based on COI gene and six species based on Cytb gene clustered monophyletic group with strong support, respectively. The optimal threshold value of Schizothorax is 0.005 based on COI gene and 0.008 based on Cytb gene. The results of genetic similarity tests performed through online BLAST showed that 108 of 185 similarity searches succeeded in identifying conspecific sequences based on COI gene and 199 of 264 succeeded in identifying conspecific sequences based on Cytb gene. Considering greater interspecific genetic distance in Kimura 2-parameter (K2P) analysis and many clades with higher supporting values in tree-based analysis, we suggest that Cytb gene has better resolution in discrimination of Schizothorax species than COI gene. However, there are still many confused clustering relationships based on molecular data currently available. Incomplete lineage sorting, the existence of possible cryptic species and problematic morphological identification, etc. might have greatly weakened the resolution of Cytb gene in discrimination of Schizothorax species.

When Nature Decides who Stays and who Goes:Priority effects Extirpating the Non-Native Brown Trout Salmo Trutta fario L. Population from a Himalayan River

Climate-induced stochastic events bring forth idiosyncratic changes in habitat and community assemblage patterns of an area. Nature governs its priorities in such incidents, where native taxa are preferred over the invasive ‘late-comers’, thus leading to extirpation of the latter, according to the concept of ‘priority effects’ 1 . This stronghold of nature strictly comes into play when an ecosystem is least altered from its natural state. River Asiganga in Uttarakhand, India was chosen as a case study to understand this theory, where cloudburst-induced flash floods are considered to be a reason for the complete wipe-out of non-native brown trout ( Salmo trutta fario ), leaving behind the native snow trout ( Schizothorax species).

Hematological and serum biochemical parameters of five freshwater snow trout fish species from river Jhelum of Kashmir Himalaya, India

Fish blood is a pathophysiological indicator of the whole body function and is thus considered as an important tool in diagnosing the structural and functional status of fish. However, the blood parameters vary between species to species and it mainly depends upon the favorable environmental conditions where the species live. The purpose of the current study is to evaluate the hematological and serum biochemical indices of five Schizothorax species: Schizothorax labiatus, S. plagiostomus, S. esocinus, S. curvifrons and S. niger in order to establish the resemblances and variations between these Schizothorax species which are inhabiting in river Jhelum. The hematological profile including hemoglobin (Hb), total red blood cell (RBC) count, hematocrit (Hct), white blood cell (WBC) count, erythrocyte sedimentation rate (ESR), and erythrocyte indices: mean corpuscular hemoglobin concentration (MCHC), mean corpuscular hemoglobin (MCH), and mean corpuscular volume (MCV) was analyzed from each Schizothorax sp. Statistical analysis showed that there were significant differences (p < 0.05) in blood parameters among five Schizothorax spp. The results showed lowest values of hematological parameters in S. niger with respect to other species, while the highest values of hematological parameters were recorded in S. plagiostomus. Significant differences (p < 0.05) in serum biochemical levels of glucose, protein, cholesterol and urea were also noted in Schizothorax spp. The differences found in the hematological profile and serum biochemical composition in these fishes can be attributed to the individual feeding behavior, tolerance and environmentally adjustable capability of the fish. However, further study is required to correlate the present study with some other parameters such as the nutrient status of the river Jhelum where these fishes live.

Phylogenetic association of Schizothorax esocinus with other Schizothoracinae fishes based on protein coding genes

Whole mitochondrial DNA (mtDNA) for Schizothorax esocinus sequence was found to be 16,591 bp with 13 protein-coding genes, 2 rRNAs genes, 22 tRNA genes, and 2 non-coding region. For estimating phylogenetic association of a species, protein coding genes of mitochondrial DNA are considered to be a great value. In this study, we sequenced protein-coding genes of Schizothorax esocinus, based upon which we compared the 23 Schizothoracinae fishes with S esocinus by phylogenetic association. We analyzed that S. esocinus to be closely associated with Schizothorax labiatus, Schizopyge niger, Schizothorax nepalensis with high-bootstrap values. Such empirical data would be important for understanding the phylogenetic relationship of Schizothorax species.

Length and weight relationships of five different fish species from northern areas of Pakistan

In present study five different species were studied from three different rivers from northern Pakistan. Specimens were collected in the period of January to December 2017 using cast nets (10–12 mm mesh size) for Barilius, Glyptothorax and Schistura species while cast nets (mesh size 1.25 × 1.25 cm) used for Schizothorax species. Total length (TL) and fork length (FL) to the nearest 0.1 cm and body weight (BW) to the nearest 0.1 g were recorded for each individual.

Retraction Note to: Comparative karyological analysis of three species of Bothriocephalus Rudolphi 1808 (Cestoda:Pseudophyllidea) from Schizothorax species of Kashmir valley.

[This retracts the article DOI: 10.1007/s12639-012-0185-1.].