Fish Species Research Articles

Molecular Insights into the Identification, Diversity and Phylogenetics of the Por`s Goatfish Upeneus pori (Actinopterygii: Syngnathiformes: Mullidae) from Odisha Coast, Bay of Bengal, India

Numerous different habitats found in marine environments are often conducive to migration and ecological adaption of various marine organisms. The inherent drawbacks of morphology-based identification systems have made it imperative to develop trustworthy genetic techniques that permit the unambiguous identification of fish species. In the present study, seven specimens of the goatfish Upeneus pori Ben-Tuvia and Golani, 1989, were recorded (February 2021) for the first time from the Odisha coast, Bay of Bengal, India. Their DNA was isolated, and mtCOI barcode regions of four specimens were amplified and sequenced successfully. The generated barcode sequences were analyzed using different molecular approaches. U. pori exhibited low genetic variation within populations (average K2P distance = 0.0046). The median joining network of U. pori was simple, with only five haplotypes, including one haplotype present in this region. The analysis of the variation of the amino acids in the mtCOI barcode sequences suggested that there were no significant variations found among U. pori of different geographical locations. The species U. pori was diverged from its common ancestor during the late Miocene sub-epoch, which was around 6.38 Mya. These findings provide insights into the population genetics and evolutionary history of U. pori in this region.

Helminths collected from some freshwater fishes and amphibians in Ecuador and Venezuela.

The present paper comprises a systematic survey of helminths (trematodes, an acanthocephalan and nematodes) found in nine species of freshwater fishes in Ecuador collected in March 1999 and those (a trematode and acanthocephalans) collected from an amphibian and two species of freshwater fishes in Venezuela in 1992, 1996 and 2001. The following 17 helminth species were recorded: Trematoda: Prosthenhystera ornamentosa sp. n., P. obesa (Diesing, 1850), Crassicutis intermedius (Szidat, 1954), C. cichlasomae Manter, 1936 and Glypthelmins eleutherodactyli sp. n. Acanthocephala: Quadrigyrus torquatus Van Cleave, 1920, Gracilisentis variabilis (Diesing, 1851) and Neoechinorhynchus (Neoechinorhynchus) ecuadoris sp. n. Nematoda: Cosmoxynema vianai Travassos, 1949, Travnema travnema Pereira, 1938, Touzeta ecuadoris Petter, 1987, Sprentascaris hypostomi Petter et Cassone, 1984, Sprentascaris sp., Contracaecum sp. Type 1 larvae, Contracaecum sp. Type 2 larvae, Procamallanus (Procamallanus) peraccuratus Pinto, Noronha et Rolas, 1976 and Procamallanus (Spirocamallanus) sp. juv. Nearly all of these parasites are reported from Ecuador or Venezuela for the first time and many of these findings represent new host records. The new species P. ornamentosa sp. n. was collected from the gall-bladder of an unidentified anostomid (Anostomidae, Characiformes) in Ecuador, G. eleutherodactyli sp. n. from the digestive tract of the frog Eleutherodactylus sp. (Eleutherodactylidae, Anura) in Venezuela and N. (N.) ecuadoris sp. n. from the intestine of Lebiasina sp. (Lebiasinidae, Characiformes) in Ecuador. Most parasites are briefly described and illustrated and problems concerning their morphology, taxonomy, hosts and geographical distribution are discussed.

From traditional to industrial use of insects as feed: a review

Abstract Insects are part of the natural diet of fish and poultry species and to a lesser extent of pigs, dogs and cats. In traditional farming, poultry gather their food in a free roaming manner, and insects are part of the diet. Similarly, a large fraction of the diet of freshwater fish consists of aquatic insects. These features are exploited by farmers all over the world, as feed costs are high. For example, farmers lure termites to baskets filled with organic matter, and the insects are then fed to chickens. They also employ light sources above fishponds to attract insects for their fish. More sophisticated methods are, for example, attracting naturally occurring houseflies to containers filled with organic waste, e.g. manure. The captured maggots or pupae are then fed to poultry. We discuss the following insect groups as feeds for poultry, pigs, fish, dogs and cats: bees, caterpillars, cockroaches, flies, grasshoppers and termites. Feed for poultry can also consist of insect pests, which are then controlled at the same time, for example ducks to control rice pests. Moreover, leftovers from the silk industry can be used to feed chickens, pigs and fish. Insects are also commonly used as bait for fishing. The interest in a more industrial production of insects such as the black soldier fly and housefly as animal feed started in the 1970s. In the last 15 years, large-scale rearing of insects for animal feed has taken off, with the industry receiving more than 1.5 billion dollars in investment. The market is expanding, the legislation is becoming more conducive, while academic interest is increasing exponentially. The environmental, nutritional and functional benefits of insects as feed are becoming more and more recognized. Insects are poised to play an increasingly prominent role in shaping the future of animal feed production.

Comparative analysis of blood protein fractions in two mediterranean farmed fish: Dicentrarchus labrax and Sparus aurata

Total protein levels in fish are widely used in health and welfare studies, providing a simple and accessible measure. However, the multifaceted role of blood proteins makes it sometimes challenging to link total protein content to specific health issues, while specific protein fractions may offer more precise insights into fish biology and health, particularly in farmed fish species where such data is often lacking. Data were gathered from two experiments involving Dicentrarchus labrax and Sparus aurata, key species in European marine aquaculture. The aim was (1) to assess how different globulin fractions contribute to total protein content in blood and (2) how these contributions vary across different sampling times in healthy animals. In D. labrax, the beta1 globulin fraction emerged as the major contributor (34.16%), followed by albumin and alpha2 globulins (18.24% and 16.41%, respectively). In contrast, pre-albumins and alpha1 fractions had the least contribution (5.49% and 7.71%). S. aurata exhibited albumin as the primary contributor (23.39%), followed by beta1 and alpha2 globulins (19.71% and 19.15%, respectively), with gamma and alpha1 fractions contributing the least (5.34% and 8.63%). Notably, the study revealed relatively stable contributions of globulin fractions to total proteins within both species, albeit with minor variations over time, potentially linked to environmental and individual factors. Furthermore, larger fish displayed higher total protein levels. This research underscores the need for further investigation into the diverse factors influencing globulin contributions to total proteins, ultimately enhancing health and welfare monitoring for farmed fish species.

High Levels of Erucic Acid Cause Lipid Deposition, Decreased Antioxidant and Immune Abilities via Inhibiting Lipid Catabolism and Increasing Lipogenesis in Black Carp (Mylopharyngodon piceus).

This study investigated the effects of dietary erucic acid (EA) on growth, lipid accumulation, antioxidant and immune abilities, and lipid metabolism in black carp fed six diets containing varying levels of EA (0.00%, 0.44%, 0.81%, 1.83%, 2.74%, and 3.49%), for 8 weeks. Results showed that fish fed the 3.49% EA diet exhibited lower weight gain, compared to those fed the 0.81% EA diet. In a dose-dependent manner, the serum triglycerides and total cholesterol were significantly elevated in the EA groups. The 1.83%, 2.74%, and 3.49% levels of EA increased alanine aminotransferase and aspartate aminotransferase activities, as well as decreased acid phosphatase and alkaline phosphatase values compared to the EA-deficient group. The hepatic catalase activity and transcriptional level were notably reduced, accompanied by increased hydrogen peroxide contents in the EA groups. Furthermore, dietary EA primarily increased the C22:1n-9 and C20:1n-9 levels, while decreasing the C18:0 and C18:1n-9 contents. In the EA groups, expressions of genes, including hsl, cpt1a, cpt1b, and ppara were downregulated, whereas the fas and gpat expressions were enhanced. Additionally, dietary EA elevated the mRNA level of il-1β and reduced the expression of il-10. Collectively, high levels of EA (2.74% and 3.49%) induced lipid accumulation, reduced antioxidative and immune abilities in black carp by inhibiting lipid catabolism and increasing lipogenesis. These findings provide valuable insights for optimizing the use of rapeseed oil rich in EA for black carp and other carnivorous fish species.

Changes at small intestine induced by food-fish contaminated with ciguatoxins

Ciguateric syndrome is a food poisoning associated with the consumption of some species of fish that have accumulated ciguatoxins (CTXs) in their tissues. The effects of the syndrome occur with nervous imbalances which have been described for quite some time, and mentioned in sailing literature for centuries. In the last decade, research has been focused on the implementation of analytical methods for toxin identification and the study of action modes of CTXs to design effective treatments. However, an important aspect is to determine the damage that CTXs caused in the organs of affected individuals. In this work, the damages observed in tissues of mice, mainly in the small intestine, were analyzed. The animals were fed with CTX-contaminated fish muscle at concentrations 10-times below the median lethal dose (LD50) for 10 weeks. The analysis of tissues derived from the oral treatment resulted in an increased occurrence of Paneth cells, presence of lymphoid tissue infiltrating the mucosa and fibrous lesions in the mucosal layer of the small intestine. A decreasing weight in animals fed with toxic muscle was observed.

Perceived effects of climate change on aquaculture production in Zambia: status, vulnerability factors, and adaptation strategies

Aquaculture plays a critical role in Zambia's food and nutrition security. However, aquaculture is highly vulnerable to the effects of a changing climate which can lead to economic losses, and food and nutrition insecurity. In this study, we investigated the perceived effects of climate change on aquaculture production in Zambia, vulnerability factors, and adaptation strategies. We used semi-structured and structured questionnaires to collect data from aquaculture producers in all provinces across the country. Results revealed high (over 80%) awareness of climate change, primarily attributed to literacy levels and access to media. Producers perceived occurrence of climate-related changes such as rising temperature, altered rainfall patterns, cyclones frequency, and disease outbreaks, impacting production costs. Generally, the results indicate a high to medium perception of rising temperature and increased frequency of flooding and droughts across the country. Although rising temperature did not appear to affect aquaculture production cost, the frequency of droughts, floods, cyclones, and disease outbreaks showed a significant association with production costs. Identified vulnerability factors include reliance on a limited range of fish species, absence of insurance coverage, and low adoption of adaptation practices. Vulnerability levels vary across regions, with provinces in agroecological zone I (Eastern, Lusaka, Southern, and Western) showing higher vulnerability. Despite this, many producers aren't implementing adaptation measures due to financial limitations, species diversity constraints, and insufficient knowledge of alternative economic pursuits. Main adaptation strategies involve livelihood diversification and adjustments in fish cultivation periods and infrastructure. To foster aquaculture sustainability amid climate change, critical interventions such as farm insurance, research diversification in aquaculture species, and enhancing producer resilience are necessary.

Parabacteroides distasonis regulates the infectivity and pathogenicity of SVCV at different water temperatures

BackgroundSpring viremia of carp virus (SVCV) infects a wide range of fish species and causes high mortality rates in aquaculture. This viral infection is characterized by seasonal outbreaks that are temperature-dependent. However, the specific mechanism behind temperature-dependent SVCV infectivity and pathogenicity remains unclear. Given the high sensitivity of the composition of intestinal microbiota to temperature changes, it would be interesting to investigate if the intestinal microbiota of fish could play a role in modulating the infectivity of SVCV at different temperatures.ResultsOur study found that significantly higher infectivity and pathogenicity of SVCV infection in zebrafish occurred at relatively lower temperature. Comparative analysis of the intestinal microbiota in zebrafish exposed to high- and low-temperature conditions revealed that temperature influenced the abundance and diversity of the intestinal microbiota in zebrafish. A significantly higher abundance of Parabacteroides distasonis and its metabolite secondary bile acid (deoxycholic acid, DCA) was detected in the intestine of zebrafish exposed to high temperature. Both colonization of Parabacteroides distasonis and feeding of DCA to zebrafish at low temperature significantly reduced the mortality caused by SVCV. An in vitro assay demonstrated that DCA could inhibit the assembly and release of SVCV. Notably, DCA also showed an inhibitory effect on the infectious hematopoietic necrosis virus, another Rhabdoviridae member known to be more infectious at low temperature.ConclusionsThis study provides evidence that temperature can be an important factor to influence the composition of intestinal microbiota in zebrafish, consequently impacting the infectivity and pathogenicity of SVCV. The findings highlight the enrichment of Parabacteroides distasonis and its derivative, DCA, in the intestines of zebrafish raised at high temperature, and they possess an important role in preventing the infection of SVCV and other Rhabdoviridae members in host fish.5bE3maafB13tm5XCByKxuZVideo

Croakers in three coastal areas of Lagos state, Nigeria: Sustainability levels and stakeholders’ perceptions on the use of ecosystem-based fisheries management

Croakers are an economically important fish species in Nigeria. Croakers are harvested by artisanal and industrial fisheries, providing a significant source of income and livelihood for coastal communities. Yet, human activities pose a significant threat to the survival of croakers in Nigeria. This study aims to evaluate the sustainability of croakers in the coastal waters of Lagos, Nigeria. The study also examines stakeholders' perceptions of Ecosystem-Based Fisheries Management (EBFM) as a tool for sustainable fisheries management in Nigeria. Questionnaires are used to collect data, and the Multidimensional Scaling Tool “Rapfish” is used to assess the sustainability level of croakers in three study areas. The results indicate that stakeholders have a positive attitude toward implementing EBFM. The sustainability analysis indicates degrees of sustainability of croakers at the boundary of being “less sustainable”. Specifically, the sustainability scores along the five dimensions analyzed are Ecological sustainability (55.69 %), economic (56.35 %), ethical (54.02 %), social (42.31 %), and technological sustainability (57.51 %). Based on these findings, the study derives several policy recommendations to improve the sustainability of croakers in Nigeria.

Different ploidy-level hybrids derived from female common carp × male topmouth culter

Distant hybridization is an effective strategy for creating polyploids in fish genetic breeding. In this study, the cross of common carp (Cyprinus carpio, 2n = 100, COC, ♀) and topmouth culter (Culter alburnus, 2n = 48, TC, ♂), which belonged to different subfamilies, was conducted and obtained surviving hybrid offspring (CT hybrids). Based on the measurement of DNA content and chromosomal numbers, three ploidy levels of CT hybrids were identified: diploid hybrids (2n = 74, 2nCT), triploid hybrids (3n = 124, 3nCT), and tetraploid hybrids (4n = 148, 4nCT). Analyses of countable traits and measurable traits indicated a significant similarity between CT hybrids and COC in comparison to TC. The genetic variation analysis of 5S rDNA and HoxD10a gene in CT hybrids revealed the retention of all COC genotypes and the partial elimination of TC genotypes, as well as the generation of novel variant genotypes (derived from TC genotypes) and recombinant genotypes (derived from parental genotypes), which suggested that in CT hybrids, the paternal subgenome exhibited greater instability than the maternal subgenome. In addition, the droplet digital PCR (ddPCR) method, combining allele-specific probes targeting the EPHX2 gene, was employed for the first time to investigate the genome composition of hybrids. The results showed that the ratios of COC-allele number to TC-allele number were approximately 1 in 2nCT, 2 in 3nCT, and 1.5 in 4nCT, respectively, which confirmed the hybridization origins for each type and effectively distinguished between the three CT hybrids. The obtainment of CT hybrids harbors potential benefits and application in aquaculture and provides an ideal model for understanding the influence of hybridization and polyploidization on the genomic composition of fish species.

A Comparative Study of Phase I and II Hepatic Microsomal Biotransformation of Phenol in Three Species of Salmonidae: Hydroquinone, Catechol, and Phenylglucuronide Formation

The in vitro biotransformation of phenol at 11 °C was studied using pre-spawn adult rainbow (Oncorhynchus mykiss) (RBT), brook (Salvelinus fontinalis) (BKT), and lake trout (Salvelinus namaycush) (LKT) hepatic microsomal preparations. The incubations were optimized for time, cofactor concentration, pH, and microsomal protein concentration. Formation of Phase I ring-hydroxylation and Phase II glucuronidation metabolites was quantified using HPLC with dual-channel electrochemical and UV detection. The biotransformation of phenol over a range of substrate concentrations (1 to 180 mM) was quantified, and the Michaelis–Menten kinetics constants, Km and Vmax, for the formation of hydroquinone (HQ), catechol (CAT), and phenylglucuronide (PG) were calculated. Species differences were noted in the Km values for Phase I enzyme production of HQ and CAT, with the following rank order of apparent enzyme affinity for substrate: RBT > BKT = LKT. However, no apparent differences in the Km for Phase II metabolism of phenol to PG were detected. Conversely, while there were no apparent differences in Vmax between species for HQ or CAT formation, the apparent maximum capacity for PG formation was significantly less in LKT than that observed for RBT and BKT. These experiments provide a means to quantify metabolic activation and deactivation of xenobiotics in fish, to compare activation and deactivation reactions across species, and to act as a guide for future predictions of new chemical biotransformation pathways and rates in fish. These experiments provided the necessary rate and capacity (Km and Vmax) inputs that are required to parameterize a fish physiologically based toxicokinetic (PB-TK) model for a reactive chemical that is readily biotransformed, such as phenol. In the future, an extensive database of these rate and capacity parameters on important fish species for selected chemical structures will be needed to allow the effective use of predictive models for reactive, biotransformation chemicals in aquatic toxicology and environmental risk assessment.

Genetic health and diversity assessment of Sturgeon species in Kazakhstan's aquaculture and natural habitats

Sturgeon species hold significant commercial and ecological value, with many listed as endangered. Understanding their genetic structure is crucial for developing effective conservation strategies. The main aim of this study is to examine the genetic structure of sturgeon, which can provide a foundation for creating strategies to conserve these species. A total of 121 sturgeon individuals were analyzed using microsatellite molecular markers (STR) to conduct the study on the genetic structure of sturgeon fish species. DNA was extracted from fin tissues using a commercial kit, and genotyping was conducted using seven microsatellite loci. Cluster analysis and principal coordinates analysis (PCoA) were performed to identify genetic differentiation among populations. The analysis showed differences in genetic diversity between the Siberian sturgeon, Russian sturgeon, and beluga samples. A deficiency of heterozygotes was discovered in artificial samples of sturgeon, indicating possible inbreeding. Genetic analysis has also revealed genetic differentiation between populations, possibly due to geographic structure or other factors. The study allows us to recommend increasing genetic diversity by introducing individuals from natural environments into sturgeon populations in aquaculture. Regular monitoring of genetic parameters in aquaculture populations and monitoring diversity dynamics are also crucial for the conservation and sustainability of sturgeon populations. The findings could help shape conservation strategies, especially in managing genetic diversity in aquaculture and reducing the risks associated with inbreeding and genetic drift.

Applying the FAO surveillance evaluation tool (SET) to assess the fish farming disease surveillance system in Spain.

EU Member States should ensure that they implement adequate health surveillance schemes in all aquaculture farming areas, as appropriate for the type of production. This study presents the results of applying the FAO's Surveillance Evaluation Tool (SET) to assess the Spanish disease surveillance system for farmed fish species, which although applied previously in livestock production, is applied here to aquaculture for the first time. Overall, there were important score differences between trout and marine fish (seabass and seabream) surveillance, which were higher for trout in the following areas: Institutional (70.8% versus 50.0%), Laboratory (91.7% versus 47.2%), and Surveillance activities (75.3% versus 61.3%). For other categories, the values were lower and no significant differences were found. However, most surveillance efforts focused only on trout, for which there are EU and WOAH listed (notifiable) diseases. In contrast, for seabream and seabass, for which there are no listed diseases, it was considered that surveillance efforts should, nevertheless, be in place and should focus on the identification of abnormal mortalities and emerging diseases, for which there are as yet no standardized harmonised methodologies.

Genetic Diversity of the Common Black Carp Strain (Cyprinus carpio var. baisenensis)

The Common Black Carp Strain (Cyprinus carpio var. baisenensis), known for its black skin, is commonly cultured in the integrated rice-agriculture (IRA) system in Guangxi province, China. This study aimed to compare the genetic diversity of three common carp strains/populations (Common Black Carp Strain, Huanghe, and Songpu) using resequencing data. The genome-based method reveals a significant difference (p < 0.05) in identified loci and SNP frequency (p < 1 × 10−6) between the Songpu (Sp) or mirror carp and Huanghe (Hh) new strain. Additionally, the Common Black Carp Strain (Bk) exhibits a higher number of Tajima’s D values, possibly due to its population size and mutations within its entire genome. The average value of population nucleotide diversity (π) for the Bk is 1.706 × 10−4 while the mean number for the Hh and Sp strains is 1.691 × 10−4 Heterozygosity analysis results indicate that the Bk has the highest F coefficient compared to the Sp and Hh hybrids. This suggests that the isolated population of the Bk may have experienced a decrease in population size as a result of environmental disturbances in the IRA system. PCA results further reveal that all individuals of the Bk, except for one, are clustered together, while individuals of the Hh form a separate group. On the other hand, Sp displays a distinct distribution pattern. The comparative study of the genetic diversity of the Bk provides baseline data on its genome makeup. Assessing genetic diversity and genetic structure is critical for fisheries management and the conservation of critically endangered fish species.

Factors Influencing Endangered Marine Species in the Mediterranean Sea: An Analysis Based on IUCN Red List Criteria Using Statistical and Soft Computing Methodologies

The Mediterranean Sea is the second largest biodiversity hotspot on earth, with over 700 identified fish species is facing numerous threats. Of more than 6000 taxa assessed for the IUCN Red List, a minimum of 20% are threatened with extinction. A total of eight key factors that affect vulnerability of marine fish species in the Mediterranean Sea were identified using the scientific literature and expert-reviewed validated databases. A database of 157 teleost fish species with threat status ranging from least concern to critically endangered was compiled. Nominal logistic curves identified the factor thresholds on species vulnerability, namely, age at maturity, longevity, and asymptotic length at 8.45 years, 36 years, and 221 cm, respectively. A second-degree stepwise regression model identified four significant factors affecting the threat category of Mediterranean fish species, namely, overfishing, by-catch, pollution, and age at maturity according to their significance. Predictive analysis using supervised machine learning algorithms was further employed to predict the vulnerability of Mediterranean marine fish species, resulting in the development of a framework with classification accuracy of 87.3% and 86.6% for Support Vector Machine (SVM) and Gradient Boosting machine learning algorithms, respectively, with the ability to assess the degree of variability using limited information.

Invasive fish species in Romanian freshwater. A review of over 100 years of occurrence reports

Effective management of invasive alien species requires location-specific strategies involving the regular update of distribution maps to identify spatial patterns, trends, and pathways of entry and the spread and hotspots of those invasions. However, a comprehensive overview of invasive alien fish species in Romania is lacking. To fill this gap, we compiled a database with occurrences of alien fish species in Romania from diverse sources, including published literature, our own field data, online databases, social media, and online questionnaires. Occurrence data covers the 1910–2022 period. From a total of 52 alien fish species reported as present in Romania’s waterways, we assigned an invasive status to 11 species, of which Pseudorasbora parva, Lepomis gibbosus, Carassius gibelio, and Ameiurus spp. are widespread. Based on the currently available occurrence records, we evaluated the presence and distribution of invasive alien fish species at the watershed level, concluding that invasive alien fish species are present in all Romanian watersheds. We identified several hotspots consistent with the main points of entry and spread of invasive alien fish species, principally located in western, central, and eastern Romania, i.e., Mures, Crisuri, and Siret watersheds.

First Record of Snakehead Gudgeon (Ophiocara porocephala) in Sorong, West Papua, Indonesia

Aims: As reported this paper, the new record of O. porocephala has helped to improved the knowledge of the species as it extends the distribution range. Study Design: Short Communication. Place and Duration of Study: This research was conducted from September to November 2021. Sampling was carried out in the Tampa Garam mangrove forest swamp located in Tampa Garam Village, Maldum Mes Distric, Sorong City. Methodology: The morphology of fishes has been the primary source of information for taxonomic and evolutionary studies. There were numerous characters available for morphological study. Results: O. porocephala had a horizontally and terminally wide mouth with a large enough distance from the posterior area of ​​the eye. O. porocephala had ideal eye spacing with small eyelids and large corneas, two dorsal fins and an anal fin each with a distance of 1 and 22mm between the dorsal fins, the anterior dorsal consists of spines fins, while the posterior was weak fins. Fish habitat was found in mangrove areas or in estuarine areas with a salinity of 11 ppt, small fish lived in shallow areas while larger fish lived in deeper areas. The brightness of the air when the fish were isolated was 100%. Oxygen levels at 4 mg/l. O. Porocephala obtained during the study, consisting of gender is 1 female and unidenified. Meanwhile, the fish size in the class 10,9-225,39 cm and gonad weight is 2,62 of female fish with categorie gonad maturity is 3. Conclusion: Based on the results of research, fish that live in mangrove areas are carnivorous, with large fish species having a total length of 18,4 cm and small fish less than 10 cm, further research needs to be carryout base on the feed habit and maturity of this fish.

Genetic diversity and population structure of Thymallus sp. in China based on morphological and molecular markers

Thymallus sp. is a native fish species distributed in the Irtysh River Basin in China. Unfortunately, environmental damage and overfishing have led to a significant decline in Arctic grayling resources, pushing them towards endangerment. However, there is a lack of comprehensive genetic information regarding the wild populations of Thymallus sp., which poses challenges for the development of effective conservation strategies for their genetic resources. In response, this study collected 180 samples from six major tributaries within the Irtysh River Basin. It conducted a thorough investigation of Thymallus sp.'s morphological and genetic variations using morphometric measurements and microsatellite markers. The results showed that the morphological differences among the six populations were relatively minor, and none of the morphological traits reached the subspecies level or higher. Genetic analysis showed that all six populations of Thymallus sp. possessed high genetic diversity, with genetic variations among populations accounting for only 6.30 % of the total variation, suggesting that the current status of the germplasm resources was relatively good. However, due to overfishing, which had led to a decline in the number of effective breeding groups, some inbreeding has occurred within populations. Moreover, the construction of dams has hindered gene exchange, leading to a certain tendency towards genetic differentiation within the populations. This was evidenced by the clustering of Burqin and Haba into one genetic group, while Kuirt, Kayit, Kalaerzis, and Crane were classified into another genetic group. This study offers an important reference for the management and conservation of Thymallus sp. populations in the Irtysh River Basin.

Ecological assessment of microplastic contamination in surface water and commercially important edible fishes off Kadalundi estuary, Southwest coast of India.

This study focuses on the Kadalundi estuary, Kerala's first community reserve, investigating the prevalence and impacts of microplastics on both the estuarine environment and selected fish species. This study presents the initial evidence indicating the consumption of microplastic particles by 12 commercially important edible fish species inhabiting the Kadalundi estuary. Analysis revealed significant accumulations of microplastic fibers within the surface water. In examining 12 fish species from demersal and pelagic habitats, microplastics were found in both the gastrointestinal tracts and gills. In the digestive tracts, microplastic fragments constituted the highest proportion (46%), while in the gills, microplastic fibers were dominant (52.4%). This study observed a prevalence of blue microplastics over other colors in both water and fish samples. Notably, demersal species showed a higher incidence of ingested microplastics. Polymer analysis identified Polypropylene (PP), Nylon, Low-Density Polyethylene (LDPE), Polyethylene (PE), Polypropylene isotactic (iPP), PE 1 Octene copolymer, and Rayon in water samples, while fish samples predominantly contained LDPE, PP, PE, and Nylon. Risk assessment utilizing the Polymer Hazard Index (PHI) categorized certain polymers as posing minor to moderate risks. Pollution Load Index (PLI) computations indicated moderate to high levels of microplastic contamination across various sampling sites in the estuary. Principal Component Analysis (PCA) revealed a lack of correlation between fish size and microplastic ingestion, underscoring environmental factors' influence on microplastic intake. The study emphasizes the implications of microplastic pollution on the fragile ecosystem of the Kadalundi estuary, posing potential risks to biodiversity and human health.

Risks and benefits associated with the consumption of three species of fish native to the Brazilian Amazon

In the Brazilian Amazon, fish is part of the diet and culture of the native population. With industrialization and the pollution of rivers, the number of cases of people contaminated by toxic pollutants present in fish has grown. Therefore, the objective of this study was to analyze three species of fish from the Amazon, the curimatã, pescada-gó, and piramutaba, to investigate the risks and benefits associated with the consumption of their muscles and livers in different seasonal periods. The amino acid and fatty acid profiles were investigated by liquid and gas chromatography, respectively. The essential elements (Cu, Fe, Mg, Na, and Zn) were quantified by flame atomic emission spectrometry, and the contaminants lead (Pb) and mercury (Hg) by flame atomic emission spectrometry and graphite furnace. Significant amounts of unsaturated fatty acids were found in muscle and liver. The polyunsaturated acids were more present in the pescada-gó and the monounsaturated in the curimatã. Contaminants (Pb and Hg) were found at levels higher than the limit allowed by Brazilian legislation. The curimatã species contributed more than 131.79% of the Hg, exceeding the tolerable weekly limit, and is considered unfit for consumption. The study demonstrated that constant biomonitoring of species traded in the region is necessary to ensure food security.