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Fish stocks that are grown under diverse environmental conditions have different biometric relationships and growth patterns. The biometric length-weight relationship (LWR) is an essential fishery assessment tool, as fish growth is continuous and depends on genetic and environmental factors. The present study attempts to understand the LWR of the flathead grey mullet, Mugil cephalus Linnaeus, 1758, from different locations. The study area encompassed its distribution in the wild across freshwater location (one), coastal habitats (eight locations), and estuaries (six locations) in India to determine the relationship between various environmental parameters. Specimens ( n = 476) of M. cephalus were collected from commercial catches and the length and weight of individual specimens were recorded. Monthly data from the study locations were extracted for nine environmental variables from the datasets downloaded from the Physical Oceanography Distributed Active Archive Center (PO.DAAC) and the Copernicus Marine Environment Monitoring Service (CMEMS) over 16 years (2002 to 2017) on the Geographical Information System platform. The parameters of the LWR, intercept ‘a’ and slope or regression coefficient ‘b’, varied from 0.005321 to 0.22182 and 2.235 to 3.173, respectively. The condition factor ranged from 0.92 to 1.41. The partial least squares (PLS) score scatter plot matrix indicated differences in the environmental variables between the locations. PLS analysis of the regression coefficient and environment parameters revealed that certain environment variables viz. , sea surface temperature, salinity, dissolved oxygen, nitrate, and phosphate, played a positive role. However, chlorophyll, pH, silicate, and iron played a negative role in influencing weight growth across various locations. The results revealed that the M. cephalus specimens from three locations, Mandapam, Karwar, and Ratnagiri, possessed significantly higher fitness to their environment than those from the other six locations. The PLS model can be used to predict weight growth under the various environmental conditions of different ecosystems. The three identified locations are useful sites for the mariculture of this species considering their growth performance, the environmental variables, and their interactions. The results of this study will improve the management and conservation of exploited stocks in regions affected by climate change. Our results will also aid in making environment clearance decisions for coastal development projects and will improve the efficiency of mariculture systems.

Background Butter catfish ( Ompok bimaculatus ) is a preferred species in South East Asia, with huge aquaculture potential. However, there is limited information about genetic stock composition due to insufficient markers. The goal of this study was to develop de novo microsatellite markers. Methods and results For sequencing, genomic SMRT bell libraries (1.5 Kbp size) were prepared for O. bimaculatus . A total of 114 SSR containing sequences were used for primer designing. Polymorphic loci were validated by genotyping 83 individuals from four distant riverine populations, viz., Brahmaputra, Bichiya, Gomti and Kaveri. A total of 30 microsatellite loci were polymorphic, of which five were found to be associated with functional genes and eight (four positive and four negative) loci were found to be under selection pressure. A total of 115 alleles were detected in all loci and PIC ranged from 0.539 to 0.927 and pair-wise F ST values from 0.1267 to 0.26002 (p < 0.001), with an overall F ST value of 0.17047, indicating the presence of population sub-structure. Cross-species transferability of 29 loci (96.67%) was successful in congener species, Ompok pabda . Conclusion The novel SSR markers developed in this study would facilitate stock characterization of natural populations, to be used in future selection breeding programs and planning conservation strategies in these species. Identified non-neutral markers will give insights into the effect of local adaptation on genetic differentiation in the natural population of this species.

Chitala chitala (Hamilton, 1822) is an economically important food fish species occurring throughout Indian rivers, which also has ornamental value. This study focuses on morphological variations in C. chitala from seven river basins across India namely; Son, Tons, Ken, Brahmaputra, Ganga, Gomti and Gandak. A truss network was constructed by interconnecting nine landmarks to generate 36 morphometric variables extracted from digital images of specimens sampled from the study locations. Transformed truss measurements were subjected to principal component analysis (PCA), canonical discriminant function analysis (CDFA) and discriminant analyses of principal components (DAPC). DAPC function coefficients performed much better in capturing the variation pattern and discrimination between the rivers which was not achieved using CDFA. Eight truss variables were identified with significant and highest loading for truss variables on principal components and coefficients on discriminant function from DAPC contributing to maximum variation between the rivers. Performance graph and functional distribution of identified truss variables clearly indicated distinction between the rivers. Thin plate spline analysis and procrustes shape analysis further showed the variation in morphology between specimens across the rivers. The significant parameters differentiating specimens from different rivers were linked to dorsal fin origin, the base of the pectoral fin and the perpendicular point on the anal fin from the dorsal fin origin. Variation in the hydrodynamics of the rivers studied might be possibly affecting the fin kinematics and consequently leading to adaption seen as phenotypic variation in C. chitala . The results showcased in the present study shall help in better understanding of intra-specific diversity which is significant for management and conservation of a species.

Land use and land cover (LULC) changes are closely associated with accelerated soil erosion and sediment transfer to stream networks, contributing to soil fertility loss and degradation of hydrological and aquatic systems. The InVEST (Integrated Valuation of Ecosystem Services and Trade-offs) model was used to spatially estimate soil loss, sediment export and sediment retention across sub-basins of Godavari River. The model, suitable for data-scarce basins, was evaluated using available observed data, demonstrating satisfactory basin-scale performance (R 2  = 0.83; Percent bias within ± 25%). Among the sub-basins, Indravati (11.97–8.56 MMT/yr), Wainganga (8.56–7.67 MMT/yr), Sabari (6.72–6.70 MMT/yr) and Penganga (4.76–4.28 MMT/yr) consistently exhibited the highest sediment load estimates during 2011–12 and 2021–22. Deciduous forests showed the highest modelled sediment retention potential, while cropland provided a secondary contribution to on-site sediment retention. A significant reduction in sediment export yield was observed in Kinnerasani (− 61.57%), Indravati (− 26.68%) and Wainganga (− 10.41%), whereas increases were observed in Manair (+ 54.87%), Pravara (+ 4.50%) and Kaddam (+ 2.05%). Most sub-basins were classified under moderately severe to severe erosion categories. In rainfed rivers of peninsular India, sediment export patterns were strongly associated with monsoon rainfall variability and concentration. This study evaluated sediment dynamics across 12 sub-basins of the Godavari River using a novel ‘precipitation concentration index-adjusted sediment export yield index’ (PCI adjusted SEYI). By integrating rainfall concentration patterns with sediment export estimates and precipitation-scaled soil tolerance limits, the index enables improved comparative prioritisation of tributaries for aquatic ecosystem management. Positive PCI-adjusted SEYI values in Pravara, Indravati and Sabari (2011–12) and Pravara and Sabari (2021–22), identify these sub-basins as priority areas for targeted soil and water conservation measures. The findings provide a practical framework for sub-basin-level sediment management and policy support in monsoon-dominated river basins.

A new species of the genus Pangasius, is described based on 17 specimens collected from the Cauvery River, India. It can be distinguished from its sister species from South and Southeast Asia, by its widely placed, small and rounded vomerine and palatine tooth plates, longer maxillary and mandibular barbels, greater vertebrae count 50 (vs. 44–48), and smaller caudal peduncle depth (6.5–8.2% SL vs. 9.89–13.09% SL). The tooth plates of the new species closely resembles that of Pangasius macronema but can be clearly distinguished from the latter by having lesser gill rakers (16–19 vs. 36–45); a smaller eye (2.4–4.4% SL vs. 5.2–9.6% SL); and larger adipose-fin base (1.5–2.9% SL vs. 0.1–1.2% SL). The mitochondrial cytochrome c oxidase (COI) gene sequence of the new species shows the genetic divergence of 3.5% and 5.1% from P. pangasius and P. silasi respectively, the two sister species found in South Asia and India. The species delimitation approaches, Poisson Tree Processes (PTP) and assemble species by automatic partitioning (ASAP) clearly resolved that the P . icaria is distinct from its sister species. Phylogenetic position of the species with its sister species was evaluated using maximum likelihood and Bayesian analysis. The discovery of this previously unknown species of genus Pangasius from the Cauvery River of peninsular India indicates important biogeographical insight that this genus migrated till the southern division of Western Ghats.

Stem cell research has come into prominence because of its applications in assisted reproductive technology and the treatment of deadly diseases. In teleost fishes, spermatogonial stem cells have been effectively used to produce surrogate gametes and progeny through germ cell transplantation technique. The present study is the first report of an innovative application of stem cell therapy in fish species for revitalising the reproductive competence of senescent individuals. Senescent male goldfish, Carassius auratus , approximately 10 years of age were procured from a fish-breeding farm and were reared locally in the lab for an additional two years. The senescence of the individuals was then evaluated and confirmed using histological analysis, gonadal index assessment, and germ-cell specific vasa gene expression. Analyses revealed absence of spermatogonial cells and other germ cells in the testes of the senescent fish ( n  = 5). Spermatogonial cells from sexually immature C. auratus male donor were isolated using discontinuous percoll gradients, labelled with the fluorescent dye PKH-26, and transplanted into the gonads of senescent C. auratus males through urogenital papilla. Six months after the transplant, spermatozoa were collected through applying gentle manual pressure on the abdomen and were observed under a microscope. All C. auratus males with the transplant had produced spermatozoa from the transplanted cells. This was confirmed by the retention of PKH-26 in the spermatozoa and diagnostic SSR locus. Gravid C. auratus females were artificially inseminated with the spermatozoa of those senescent males and natural spawning was allowed. As a result viable progeny were produced. These observation suggests that the reproductive competence of senescent male fishes can be revitalised through spermatogonial stem cell therapy to produce functional gametes.

Garra ngopi sp. n., a new Labeoninae species, is described from the Tinam stream of the Tissa River (district Longding), which is a headwater of the Brahmaputra River basin in Arunachal Pradesh, North–Eastern India. The new species is distinguished from its congeners by the following combination of characters: smooth snout with 7–8 shallow pits forming a pseudo groove structure on anterior most of snout; 4–5 shallow pits on both sides of snout, 2 + 2 shallow pits on rostrum midst of snout; 11–13 shallow pits situated in between nares; dorsal, pectoral and pelvic fins spread with two to four smooth and shallow pits; caudal fin rays spread with numerous shallow pits are very distinct. Head without proboscis; 35–36 lateral line scales; 9–10 predorsal scales; absence of scales on chest and belly. Evidences of genetic analyses (genetic distance, phylogenetic clustering and species delimitation), on the basis of mitochondrial gene (cox1) indicated that the species was distinct from other known congeners.

This study provides the first high-quality draft genome assembly (762.5 Mb) of Tenualosa ilisha that is highly contiguous and nearly complete. We observed a total of 2,864 contigs, with 96.4% completeness with N 50 of 2.65 Mbp and the largest contig length of 17.4 Mbp, along with a complete mitochondrial genome of 16,745 bases. A total number of 33,042 protein coding genes were predicted, among these, 512 genes were classified under 61 Gene Ontology (GO) terms, associated with various homeostasis processes. Highest number of genes belongs to cellular calcium ion homeostasis, followed by tissue homeostasis. A total of 97 genes were identified, with 16 GO terms related to water homeostasis. Claudins, Aquaporins, Connexins/Gap junctions, Adenylate cyclase, Solute carriers and Voltage gated potassium channel genes were observed to be higher in number in T. ilisha , as compared to that in other teleost species. Seven novel gene variants, in addition to claudin gene (CLDZ), were found in T. ilisha. The present study also identified two putative novel genes, NKAIN3 and L4AM1, for the first time in fish, for which further studies are required for pinpointing their functions in fish. In addition, 1.6 million simple sequence repeats were mined from draft genome assembly. The study provides a valuable genomic resource for the anadromous Hilsa. It will form a basis for future studies, pertaining to its adaptation mechanisms to different salinity levels during migration, which in turn would facilitate in its domestication.

Olyra sancta, a new anguilliform bagrid catfish is described from the Tissa River, Brahmaputra River drainage in Arunachal Pradesh, north-eastern India. The new species differs from its congeners by the following combination of characters: adipose fin separate from upper principal caudal-fin rays; interorbital distance 32.2–33.9% head length (HL); eye diameter 7.0–9.0% HL; body depth at anus 6.6–9.7% standard length (SL); and caudal peduncle depth 4.2–5.3% SL. Mitochondrial gene cytochrome c oxidase subunit I was employed to determine variation at molecular level. Sequence analysis (655bp) was done along with closely related species. The results from interspecific genetic distance, phylogenetic tree (ML & NJ) and species delimitation (PTP) clearly separated the new species from its congeners.

Iatrogenic palatal perforation in infants is a rare but serious complication that can lead to feeding difficulties, aspiration and inadequate weight gain. This case report describes an infant who developed a palatal defect following hospitalisation for an acute febrile illness. After ruling out congenital and infectious aetiologies, the perforation was considered likely to be iatrogenic secondary to orotracheal intubation. A self-retentive feeding plate was fabricated and fitted to improve feeding and prevent further complications. The appliance effectively restored feeding efficiency, reduced nasal regurgitation and facilitated spontaneous healing. Over 1 month, the defect size diminished significantly, reflecting the regenerative capacity of oral tissues. This case report emphasises the importance of careful airway management, early prosthetic intervention and a multidisciplinary approach in managing such neonatal complications.