Geometric morphometric analysis was applied to assess shape divergence and population structuring between farmed and wild populations of Heteropneustes fossilis in Bangladesh. A total of 114 specimens were sampled from three farmed populations (Bogura, Dinajpur, and Mymensingh) and one wild riverine population (Garbheswari River). Landmark-based geometric morphometrics were used to quantify shape variation, which was analysed using Coefficient of Variation (CV), Principal Component Analysis (PCA), Mahalanobis distances, Discriminant and Canonical Discriminant Analyses (DFA/CDA), Multidimensional Scaling (MDS) and UPGMA clustering. The wild river population exhibited higher within-population morphological variability, indicating greater phenotypic plasticity under natural environmental conditions compared with farmed stocks. PCA revealed a dominant axis of shape variation, with the first principal component explaining 88.18% of total variance and mainly associated with differences in body depth, head profile, and fin-base positioning. Multivariate analyses consistently demonstrated clear morphometric differentiation among populations, with the Bogura farmed stock showing the greatest divergence. DFA and CDA showed strong discriminatory power (canonical correlation r = 0.844), with population separation primarily driven by variation in the anterior body region, trunk depth, and caudal peduncle morphology. These findings demonstrate robust, low-dimensional shape divergence in H. fossilis, emphasizing the effects of habitat and hatchery practices, and highlighting the importance of conserving wild morphotypes for sustainable aquaculture and broodstock management.
Spawning aggregations, schooling behaviour and twice-yearly recruitment make the shoemaker spinefoot rabbitfish (Siganus sutor) a major artisanal and subsistence fishery species in the Western Indian Ocean. However, published estimates of its maximum age and growth parameters vary considerably. In this study, we estimate the longevity of S. sutor at 4 years and an asymptotic length of 287.29 mm FL. When analysed by sex, males exhibited a larger L infinity (292.53 mm FL) than females (284.52 mm FL), yet likelihood-ratio tests and confidence ellipses formulated around L infinity and K values indicated no significant sex-based differences in growth profiles. Consistent with previous studies, S. sutor is short-lived, grows rapidly and experiences high mortality yet remains resilient to fishing pressure. However, given its importance to coastal fisheries throughout the Indian Ocean, we recommend a comprehensive, spatially comparative assessment of S. sutor life-history traits and population dynamics across its geographic range. This is necessary to determine whether inconsistencies in age and growth reported in the literature are due to the presence of a species complex with differing growth rates, mortality, behaviour or vulnerability to fishing.
This study presents a data-driven, nonlethal approach for estimating age and maturity in Oblada melanura, a commercially important member of the family Sparidae inhabiting the Mediterranean Sea. A multilayer perceptron artificial neural network (MLP ANN) with architecture (1, 10, 2) was developed using 5112 records from published literature, institutional reports, and global databases. The model uses only total length as input, eliminating destructive sampling such as otolith extraction or gonad dissection. Trained and validated in MATLAB R2024a, it achieved very high predictive accuracy, with correlation coefficients exceeding 0.999 across training, validation, and test sets, and mean squared error below 0.009. This performance likely reflects the strong length-age relationship in O. melanura during its primary growth phase (2-6 years) in the Eastern Mediterranean. For maturity classification, accuracy reached 92.3% (precision = 0.91, recall = 0.93, F1-score = 0.92), based on histologically confirmed data from Syrian coastal populations. Results indicate that age and maturity can be predicted accurately under current sampling conditions, supporting ethical and sustainable monitoring. The method reduces time, cost, and technical complexity compared to traditional or deep learning-based approaches. When benchmarked against a linear regression model on the same test dataset (n = 767), the ANN showed markedly superior performance (R = 0.9995 vs. 0.9796; MSE = 0.0068 vs. 0.4041), confirming its ability to capture nonlinear biological patterns. Although the full dataset is not publicly available due to collaborative agreements, the methodology is fully described. The trained MLP model (1-10-2) is available from the corresponding author for noncommercial academic use under a standard data use agreement, with plans to release a standalone version via a public repository. Originally developed for threatened species, this framework demonstrates robust performance in O. melanura, highlighting its potential as a standardized, low-impact tool for fish population assessment in the Eastern Mediterranean.
Despite their importance in understanding stream food webs and community dynamics, small-bodied and nongame fish remain relatively understudied. This is also true of the basic ecology for these taxa, such as calculating length-weight relationships (LWRs). Here we present LWRs for 22 species including nongame and small-bodied taxa from eastern North America in the Susquehanna River watershed in > 30 small watersheds across four years, seven families, and > 7500 individuals. To contextualize these LWRs, we compared the slopes (b) of our relationships for abundant species across broad-scale watersheds, over time, and to published slopes in eastern North America. We found significant variability in b for our four most abundant species: Rhinichthys atratulus (blacknose dace), Semotilus atromaculatus (creek chub), R. cataractae (longnose dace), and Etheostoma olmstedi (tessellated darter) across both watershed and year of sampling yet inconsistent changes across species. We also found published values for b to be > 0.1 different from our LWRs for 36% of species, indicating wide variability across their geographic range as well. Collectively, these results highlight variability in LWRs, and while they may caution against the generalized use for management, they also identify opportunities for LWR use as a tool for comparing populations. The addition of these equations to the literature fills an important gap in our understanding of LWRs for eastern North American fishes, while also providing regional, temporal, and taxonomic context for consistency of LWRs across these species.
This study examined the impact of short-term starvation on oxidative stress and antioxidant defense mechanisms in juvenile Asian sea bass (Lates calcarifer). Juvenile fish (35 +/- 9 g) were randomly allocated to 12 300 L fiberglass tanks (15 fish/tank) following acclimation. Experimental treatments (in triplicate) consisted of starvation periods of 2, 4, and 8 days, each followed by 16 days of refeeding, alongside a continuously fed control group. Fish were hand-fed a commercial diet to satiation twice daily. Liver and muscle tissues were sampled poststarvation and postrefeeding, following euthanasia with 2-phenoxyethanol. Growth performance; lipid peroxidation (malondialdehyde, MDA); and activities of key antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were assessed. Starvation significantly influenced weight gain, with the 8-day group exhibiting reduced growth compared to other treatments (p < 0.05). Antioxidant enzyme activities in muscle tissue remained unchanged across treatments; however, liver samples from the 8-day starvation group showed significant alterations in antioxidant indices (p < 0.05). These findings indicate that hepatic antioxidant defense is more responsive to starvation period than muscle tissue is and that starvation period of 8 days or longer may induce oxidative stress in the liver.
This study estimated the length-weight relationships (LWRs) of 10 fish species from the middle stretch of the Middle Uruguay River basin, aiming to provide new morphometric data and contribute to the knowledge of Neotropical ichthyofauna. Fish were collected at seven sites with sampling conducted at each site during every season, totaling 84 sampling campaigns between May 2016 and February 2019. Different fishing gears were used, including gillnets (15-80 mm), three-panel nets (150.30.150; 150.40.150; 150.50.150 mm), a beach seine (8 mm), and longlines (100 m, 30 hooks, sizes 5/0 and 12/0) baited with small fish, maize, and snails. The parameters a and b of equation W = aLb were estimated for each species, revealing five species with positive allometry, two with isometry, and three with negative allometry. The b coefficient ranged from 2.456 in Pseudoplatystoma corruscans to 3.336 in Acestrorhynchus pantaneiro. These records expand the current database on the regional ichthyofauna and provide relevant information for conservation and fisheries management in the middle stretch of the Uruguay River basin.
As a natural "green" feed additive, Chinese herbal medicines (CHMs) are extensively used in aquaculture. Nevertheless, little information is obtainable regarding the performance of CHMs on the composition of gastrointestinal microbiota in healthy juvenile Pelodiscus sinensis. Here, we investigated the intestinal microbial community composition of P. sinensis fed with artificial feed added with CHM feeding additive. Three hundred juvenile P. sinensis (3.92 +/- 0.08 g) were randomly divided into 5 groups in quadruplicate. 0.0%, 1.0%, 2.0%, 3.0%, and 4.0% of CHMs were added to the control group (CG), test group 1 (TG1), test group 2 (TG2), test group 3 (TG3), and test group 4 (TG4), respectively. After the aquaculture experiment was completed, the intestinal microbial community of P. sinensis was examined by 16S rDNA sequencing method. The results showed that the relative abundance of Proteobacteria and Firmicutes were the two most dominant phyla, and there were significant differences in TG1, TG2, TG3, and TG4 compared to the CG. The abundance of phylum Proteobacteria and genus Citrobacter increased with the increase of the dose of CHMs (p < 0.05), while a clear decrease in the relative abundance of phylum Firmicutes and genus Romboutsia, genus unclassified_f_Enterobacteriaceae, and genus Clostridium_sensu_stricto_1 was observed in the CHMs groups (p < 0.05), which could be considered as the indicators of the medication due to CHMs as a feed additive modulating the gut microbiota. The results of this study indicated that dietary supplementation with 2.0% of CHM feeding additive could significantly improve the intestinal microbiota composition of juvenile P. sinensis.
We report the first sighting of the yellowbar angelfish Pomacanthus maculosus (Forssk & aring;l, 1775) (Teleostei, Pomacanthidae) in Greece. We observed a young adult multiple times in the summer of 2025 over the course of 10 weeks on a rocky pinnacle on the island of Crete. Identification was based on visual underwater observations and analysis of video material. P. maculosus is a coral reef fish native to the western Indian Ocean. We suggest that the individual reached the Mediterranean through the Suez Canal, possibly aided by the intense ship traffic around our study location.
Aquaculture accounts for around 50% of global seafood production, with its contribution expected to expand significantly in the coming decade. While countries in the Arabian Gulf region are leveraging aquaculture to meet rising seafood demand and enhance food security, Kuwait's sector remains largely underdeveloped. In this paper, challenges and opportunities for aquaculture intensification in Kuwait are identified, emphasizing the need for the development and intensification of farmed species and the adoption of sustainable farming systems. By examining case studies, existing aquaculture endeavors, and current regulatory frameworks, a roadmap is proposed for the sustainable expansion of Kuwait's aquaculture industry, which underscores the biological, economic, and regulatory dimensions. Recommendations include suitable species and systems for farming; considerations for local supply chain production; and ramping up aquaculture production while diversifying farmed species and farming systems will be critical in the future of Kuwait's seafood security.
The progression of oocyte development and patterns of oocyte recruitment are key indicators of reproductive strategy in fishes. The present study examines, for the first time, the fecundity strategy of cage-reared Etroplus suratensis in Vembanad Lake using four indicators: (a) the oocyte size frequency distribution across ovarian reproductive phases and sampling months; (b) the proportional distribution of the oocyte developmental stages across each ovarian reproductive phase; (c) seasonal trends in the mean diameter of advanced vitellogenic oocytes; and (d) the seasonal incidence of oocyte atresia. The samples were collected monthly from October 2023 to September 2024, with 202 ovaries categorized by macroscopic observation into various ovarian reproductive phases. From these, 54 ovaries representing all ovarian reproductive phases were selected for histological examination and image analysis techniques. Histological examination identified seven distinct oocyte development stages in addition to postovulatory follicles and atretic oocytes. The oocyte size distribution revealed asynchronous oocyte development and continuous secondary growth, with no distinct separation between previtellogenic and vitellogenic oocytes. Gaussian mixture model analysis identified five distinct oocyte size clusters corresponding to successive developmental stages, confirming the presence of multiple cohorts. Logistic regression showed that the size at which 50% of oocytes recruited into vitellogenesis decreased across spawning-capable phases, reflecting rapid oocyte recruitment during repeated spawning events. A seasonal decline in the mean diameter of advanced vitellogenic oocytes was evident during the spawning season, indicating the continuous replenishment of oocytes within the advanced vitellogenic pool. A relatively stable proportion of cortical alveolar and vitellogenic oocytes during the spawning season suggests continuous recruitment of oocytes into the vitellogenic pool through de novo vitellogenesis. Furthermore, an increased occurrence of atretic oocytes was noticeable towards the end of the spawning season (i.e., August to October), reflecting a common strategy in species with indeterminate fecundity to reabsorb surplus oocytes. These findings demonstrate that E. suratensis exhibits asynchronous oocyte development, continuous oocyte recruitment and batch spawning with an indeterminate fecundity pattern. This reproductive strategy observed supports prolonged spawning activity and provides important implications for brood stock management and seed production in estuarine cage culture systems.
The lack of biometric data on chondrichthyan species has impeded the implementation of management strategies essential for the conservation of sharks and rays captured using different fishing gears in coastal ecosystems. This study aims to assess morphometric relationships (length-weight [LW], length-dorsal length [DL], and length-disc width [DW]) and the relative weight condition factor (K-rel) of 14 elasmobranch species caught by shrimp trawls in the Bah & iacute;a Magdalena-Almejas (BMA) lagoon system in Mexico from February to December 2014-2022. The length-weight relationships (LWRs) (pooled sexes, females and males) were calculated using the potential model. The growth (allometric or isometric) was determined by comparing the b values for each elasmobranch species with the isometric value (b = 3.0) using the t-Student test. Length-length (LL) relationships were determined by applying the linear regression model. Given the body condition is commonly used as a biometric tool to indicate the overall health and energetic status of fish in relation to growth, the K-rel was calculated. The assessment was conducted on 440 elasmobranch specimens (70 sharks and 370 rays) across 14 species, 9 genera, and 8 families. The genus Urobatis was the most abundant in the total elasmobranch catches obtained (n = 203). The parameter b of the LW relationships varied from 2.57 (Heterodontus mexicanus) to 3.87 (Mustelus lunulatus). Most morphometric relationships (LDL and LDW) showed a significant statistical correlation (r(2) > 0.85; p < 0.05). The condition factor analysis indicated that most (86%) elasmobranch species were in good somatic condition (K-rel >= 1). This study represents the first reference data on the LWRs for the Mexican Horn Shark (H. mexicanus), as well as the first assessment on LL relationships (DL and DW) and the relative weight condition factor for all elasmobranch species included. Consequently, this research helps bridge the information gap regarding shark and ray species, contributing to the monitoring and population assessment of bycatch elasmobranchs in the BMA lagoon system.
The Oujiang River, the second-largest river in Zhejiang Province, southern China, supports rich fishery resources. However, these resources have experienced significant decline due to multiple anthropogenic and environmental pressures. To assess the current status of fishery resources, this study investigated the length-weight relationships (LWRs) and length-length relationships (LLRs) of 11 economically and ecologically important fish species. The results showed that the b values ranged from 2.534 to 3.469, with the coefficient of determination (r2) ranging from 0.893 to 0.987. Notably, we provide the first LWR and LLR records for Acrossocheilus fasciatus and Microphysogobio oujiangensis in FishBase, along with a new maximum length record for Onychostoma barbatulum. These findings offer valuable baseline data to inform science-based conservation and sustainable management of fisheries in the Oujiang River.
Traccatichthys is a genus of small benthic omnivorous nemacheiline loaches, with limited ecological and biological data available. Here, we described length-weight relationships (LWRs) for four Traccatichthys species from southern China. Fishes were sampled using stationary fish cages (10 m in length, mesh size: 0.5 cm) between January and April 2025 at four selected sampling sites. All specimens were transported to the laboratory within 2 days of collection, maintained alive in oxygenated water, and measured for total length (TL) to the nearest 0.1 cm and body weight (BW) to the nearest 0.01 g in the laboratory. LWRs were calculated using linear regression, and the four species-specific models were all highly significant (p < 0.001). The allometric exponent b values ranged from 2.875 to 3.196. The LWRs for three species (T. tuberculum, T. zispi, and T. taeniatus) are new to FishBase (as of May 2025). Our results provide essential baseline data for sustainable management and ecological research of these species.
This study developed predictive models using generalized linear statistical analyses to estimate Atlantic bonefish (Albula vulpes) fork length (FL) dependent on four head morphometry covariates: snout length, eye diameter, postorbital head length, and head length. A total of 257 South Florida bonefish were examined, which ranged from 28 to 720 mm FL. Each of the morphometric measurements was highly correlated with FL, with coefficients of determination (r2) that ranged from 0.9592 for eye diameter to 0.9959 for head length. Total length (TL) was also highly correlated with FL. Sex differences in the morphometric measurements were examined; however, no significant sexual dimorphism was detected. All of the morphometric measurements examined were good predictors of Atlantic bonefish FL and TL.
To assess the changes in genetic structure across generations of selectively bred largemouth bass ( Micropterus nigricans ) (F3, F4, F5, and F6), this study, in combination with an introduced population, utilized 15 pairs of microsatellite primers to analyze the genetic diversity and structure. The results revealed a total of 62 alleles ( N a ), with an average of 4.160 alleles per locus. The average observed heterozygosity ( H o ) was 0.559, and the average expected heterozygosity ( H e ) was 0.529. The introduced population exhibited the highest genetic diversity parameters, including polymorphic information content (PIC), N a effective number of alleles ( N e ), H o , H e , and Shannon’s information index ( I ). In contrast, the selectively bred populations showed a gradual decline, with PIC ranging from 0.398 to 0.494, N a from 3.533 to 4.000, N e from 2.008 to 2.387, H o from 0.480 to 0.589, H e from 0.457 to 0.550, and I from 0.794 to 0.990, indicating a moderate level of polymorphism. The F -test in different generations of selectively bred populations revealed that 10 loci had negative inbreeding coefficients ( F is ), while 5 loci had positive values, suggesting a low level of inbreeding across generations. Overall, the introduced and selectively bred populations exhibited a moderate level of genetic differentiation, with low to moderate genetic differentiation observed. AMOVA revealed that 92% of the variation originated within individuals. UPGMA clustering and PCoA analysis demonstrated significant genetic differentiation between the selectively bred populations and the introduced population. In conclusion, the introduced population exhibited higher genetic diversity compared to the selectively bred populations. The genetic diversity of the selectively bred populations showed a declining trend as the selection process progressed, highlighting the importance of evaluating genetic diversity while improving target traits during selection. This study provides scientific guidance for the selection of new varieties and the evaluation and conservation of germplasm resources in largemouth bass.
Aquaculture genomics, genetics, and breeding are pivotal disciplines that enhance the efficiency and sustainability of fish farming. The advanced genomic technologies, including whole genome sequencing (WGS), genome-wide association studies (GWAS), and CRISPR/Cas9 gene editing, have revolutionized our understanding of the genetic foundations of economically important traits in aquaculture species. These technologies enable the identification of genetic markers linked to growth, disease resistance, and environmental adaptability, facilitating the development of improved breeding strategies. Marker-assisted selection (MAS) and genomic selection (GS) are now integral to breeding programs, allowing precise selection of desirable traits and accelerating genetic gain. Despite these advances, several challenges remain, including the need for extensive phenotypic and genomic databases, the complexity of polygenic traits, and ethical considerations surrounding genetic modifications. Furthermore, integrating these genomic tools into practical breeding programs necessitates bioinformatics infrastructure and expertise. This review provides a comprehensive overview of the present status of aquaculture genomics and genetics, highlighting key technological advancements and their applications in breeding programs. It also discusses the challenges faced by the industry and outlines future research priorities, such as enhancing genomic resources for under-researched species, improving phenotypic data collection accuracy, and developing sustainable breeding practices. By addressing these challenges and leveraging genomic insights, the aquaculture industry can significantly improve productivity, sustainability, and resilience, contributing to global food security and economic growth.
The pallid sturgeon Scaphirhynchus albus , a large, long-lived fish endemic to the Missouri and Mississippi River Basins, was listed as a federally endangered species in 1990 due to population declines driven by profound anthropogenic habitat alterations, including river fragmentation by dams and channelization. In contrast, its congener, the shovelnose sturgeon Scaphirhynchus platorynchus , remains common in large rivers and their tributaries, such as the Des Moines River. Historically, the pallid sturgeon’s range in Iowa has been limited to the Missouri River along the state’s western border. Recovery efforts, as outlined in the National Pallid Sturgeon Recovery Plan, have emphasized habitat restoration and conservation stocking to prevent extirpation and to support natural recruitment. Here, we document the first verified records of wild (nonstocked) pallid sturgeon in the Des Moines River, Iowa. This represents a potential expansion of the species’ known contemporary range and occurs within a tributary not previously identified as occupied habitat. This finding underscores the potential for stocked or wild individuals to disperse into novel river systems where previously undocumented habitat may be available. The finding has immediate conservation implications under the Endangered Species Act, prompting a reassessment of the Des Moines River’s management strategies and necessitating enhanced, targeted sampling efforts. It also raises concerns under the Act’s Similarity of Appearance clause, which governs the legal commercial take of shovelnose sturgeon in the pooled reach of the Upper Mississippi River downstream of the Des Moines River confluence, a potential migration corridor. The presence of pallid sturgeon in the Des Moines River demonstrates that even highly altered river systems can provide essential habitat, such as suitable spawning substrate, needed to support their life cycle, particularly when stream flow is managed to approximate natural hydrologic patterns.
The European eel ( Anguilla anguilla L. 1758) is a migratory fish species whose populations have undergone a severe collapse in numbers in recent decades. Infectious diseases are one of the factors contributing to the decline of European eels. One hundred and eighteen eels from four Spanish Mediterranean sites were captured and analysed for Anguillicoloides crassus , anguillid herpesvirus 1 (AngHV1), rhabdovirus Eel Virus European X (EVEX) and aquabirnavirus Eel Virus European (EVE). The nematode A. crassus and AngHV1 were present in eels from all four sampled wetlands, which indicates that these two pathogens are commonly occurring in Mediterranean ecosystems. The global prevalence (eels from the four wetlands) of the later parasite stages (L3, L4 and adults) was 74.58%. The global prevalence of all parasite stages (L2, L3, L4 and adults) was 93.22%. The global prevalence of the AngHV1 virus was 27.7%. EVEX was only detected in eels from two of the four wetlands (12.87% global prevalence), while EVE was not detected in any sample. At the population level, pathogens seem to represent a serious threat to eels in L’Albufera de Valencia: 92.31% of specimens were co-infected by AngHV1 and EVEX and 84.62% of specimens were triple co-infected with AngHV1, EVEX and any stage of A. crassus . Further studies are necessary to understand the impact of diseases, together with other anthropogenic factors (pollution, salinity, climatic change, etc.), on eel status in Mediterranean ecosystems.
Mongolian grayling is a large piscivorous grayling endemic to the endorheic basin of the Khovd and Zavkhan River systems in western Mongolia. Ongoing large-scale hydropower development in the Khovd River has raised concerns about potential impacts on the Mongolian grayling populations in the area. Very little is known about the behavior and biology of Mongolian grayling, which makes it difficult to predict the impacts of damming and to plan for conservation and management mitigation actions. In this study, we used acoustic telemetry to track migration and survival of Mongolian grayling in the Khovd River system before the onset of hydropower construction. We found that the Mongolian grayling in the Khovd River conduct extensive seasonal migrations (> 170 km) to reach overwintering and spawning habitat and that migration routes pass through the Shijigtiin Canyon which is currently being developed for hydropower. We also found that Mongolian grayling in the downstream Khar Lake predominantly reside in the lake and only use lotic habitat during the spawning season, including the dammed Chono-Kharaikh River. Based on our results, we argue that the ongoing hydropower development of the Khovd River will have severe impacts on the grayling population by disrupting the annual migration cycle, prohibiting access to spawning and overwintering habitat, and altering flow regimes on downstream spawning grounds.
