Fish Gills Research Articles

Determination of Heavy Metals in Etroplus suratensis from Koggala Lagoon in Southern, Sri Lanka

Fish is one of the best organisms in many scientific studies to evaluate heavy metal pollution and human health hazards as they are well-understood organisms in the aquatic environment. The present study was carried out to examine the level of heavy metals in different tissues of Etroplus suratensis (Green chromide) in Koggala lagoon, Sri Lanka. Atomic absorption spectrophotometer (AAS) was used to determine the levels of copper (Cu2+), cadmium (Cd+3), lead (Pb+2) and Chromium (Cr+3) ions in the different tissues (skin, liver, gill, and flesh) of fish belonging to three different sizes; small (7.8-10.2) cm, medium (14.1-16.6) cm, and large (19.8-25.2) cm. The number of thirty-six fish were collected from the lagoon randomly. According to available sizes, 12 fish for each size class were used for the analysis. Furthermore, the histological analysis was carried out to identify the changes at the tissue levelling the gill and liver of fish in three different size classes. Heavy metal concentration in fish samples were compared with the standard levels of heavy metals. Heavy metal concentrations in body tissues of three different body sizes of fish were found to be mainly in the order of Cu>Pb>Cr> Cd. The highest concentrations (P<0.05) of heavy metals were found in the fish flesh and skin, while the lowest concentrations were found in the gills. The range of heavy metal concentrations (g g-1 dry weight) in body tissue of small size, E. suratensis fish were, Cu: 0.0443-0.6210, Cd: 0.0110–0.0214, Pb: Below Detection Level (BDL)- 0.46 and Cr: BDL-39.633, Medium size fish were, Cu: 0.0713–0.6210, Cd: 0.0134-0.0170, Pb: BDL-40.906, Cr: 0.0014–0.0500 and large fish were, Cu: 0.0553–0.345, Cd: 0.0110–0.0256, Pb: 0.0204–0.2103 and Cr: 0.0194–0.0773. However, Cd, Cr and Pb concentrations of flesh tissues were under the standard recommended limits referred by the FAO. Through the Cu concentration in flesh, tissues exceeded the standard limits of FAO. It is not considered as a toxic heavy metal. Histological analysis revealed that the deviation of shape of hepatic cells in the liver may due to the exposure to heavy metals in the lagoon. According to the overall result, biomagnification nature of heavy metals, and the consumption of E. suratensis in the Koggala the bioaccumulation and lagoon may create health hazards to consumers. 
 Keywords: Green chromide, Koggala Lagoon, Heavy metals, Histology

Molecular identification, phylogenetic analysis and histopathological study of pathogenic free-living amoebae isolated from discus fish (Symphysodon aequifasciatus) in Iran: 2020–2022

Free-living amoebae (FLA) are capable of inhabiting diverse reservoirs independently, without relying on a host organism, hence their designation as “free-living”. The majority of amoebae that infect freshwater or marine fish are amphizoic, or free-living forms that may colonize fish under particular circumstances. Symphysodon aequifasciatus, commonly referred to as the discus, is widely recognized as a popular ornamental fish species. The primary objective of the present study was to determine the presence of pathogenic free-living amoebae (FLA) in samples of discus fish. Fish exhibiting clinical signs, sourced from various fish farms, were transferred to the ornamental fish clinic. The skin, gills, and intestinal mucosa of the fish were collected and subjected to culturing on plates containing a 1% non-nutrient agar medium. The detection of FLA was conducted through morphological, histopathological and molecular methods. The construction of the phylogenetic tree for Acanthamoeba genotypes was achieved using the maximum likelihood approach. The molecular sequence analysis revealed that all cultures that tested positive for FLA were T4 genotype of Acanthamoeba and Acanthamoeba sp. The examination of gill samples using histopathological methods demonstrated the presence of lamellar epithelial hyperplasia, significant fusion of secondary lamellae, and infiltration of inflammatory cells. A multitude of cysts, varying in shape from circular to elliptical, were observed within the gills. The occurrence of interlamellar vesicles and amoeboid organisms could be observed within the epithelial tissue of the gills. In the current study, presence of the Acanthamoeba T4 genotype on the skin and gills of discus fish exhibiting signs of illness in freshwater ornamental fish farms was identified. This observation suggests the potential of a transmission of amoebic infection from ornamental fish to humans, thereby highlighting the need for further investigation into this infection among ornamental fish maintained as pets, as well as individuals who interact with them and their environment.

Characterization of gill bacterial microbiota in wild Arctic char (Salvelinus alpinus) across lakes, rivers, and bays in the Canadian Arctic ecosystems.

Teleost gill mucus has a highly diverse microbiota, which plays an essential role in the host's fitness and is greatly influenced by the environment. Arctic char (Salvelinus alpinus), a salmonid well adapted to northern conditions, faces multiple stressors in the Arctic, including water chemistry modifications, that could negatively impact the gill microbiota dynamics related to the host's health. In the context of increasing environmental disturbances, we aimed to characterize the taxonomic distribution of transcriptionally active taxa within the bacterial gill microbiota of Arctic char in the Canadian Arctic in order to identify active bacterial composition that correlates with environmental factors. For this purpose, a total of 140 adult anadromous individuals were collected from rivers, lakes, and bays belonging to five Inuit communities located in four distinct hydrologic basins in the Canadian Arctic (Nunavut and Nunavik) during spring (May) and autumn (August). Various environmental factors were collected, including latitudes, water and air temperatures, oxygen concentration, pH, dissolved organic carbon (DOC), salinity, and chlorophyll-a concentration. The taxonomic distribution of transcriptionally active taxa within the gill microbiota was quantified by 16S rRNA gene transcripts sequencing. The results showed differential bacterial activity between the different geographical locations, explained by latitude, salinity, and, to a lesser extent, air temperature. Network analysis allowed the detection of a potential dysbiosis signature (i.e., bacterial imbalance) in fish gill microbiota from Duquet Lake in the Hudson Strait and the system Five Mile Inlet connected to the Hudson Bay, both showing the lowest alpha diversity and connectivity between taxa.IMPORTANCEThis paper aims to decipher the complex relationship between Arctic char (Salvelinus alpinus) and its symbiotic microbial consortium in gills. This salmonid is widespread in the Canadian Arctic and is the main protein and polyunsaturated fatty acids source for Inuit people. The influence of environmental parameters on gill microbiota in wild populations remains poorly understood. However, assessing the Arctic char's active gill bacterial community is essential to look for potential pathogens or dysbiosis that could threaten wild populations. Here, we concluded that Arctic char gill microbiota was mainly influenced by latitude and air temperature, the latter being correlated with water temperature. In addition, a dysbiosis signature detected in gill microbiota was potentially associated with poor fish health status recorded in these disturbed environments. With those results, we hypothesized that rapid climate change and increasing anthropic activities in the Arctic might profoundly disturb Arctic char gill microbiota, affecting their survival.

Fish gill surface area can keep pace with metabolic oxygen requirements across body mass and temperature

Abstract Climate warming is driving the maximum attainable size of many fish species to decrease, yet the mechanisms underlying this ‘shrinking’ phenomenon are not well understood. The gill oxygen limitation (GOL) hypothesis is perhaps the most prominent mechanistic proposition, asserting that, as fish grow, the two‐dimensional gill surface area (GSA) progressively fails to supply enough oxygen to support the continued growth of the three‐dimensional body—a process exacerbated by increased metabolism associated with warming. However, these ideas have been hotly debated owing to limited empirical understanding of how GSA develops with respect to a fish's body mass and oxygen requirements. For the first time, we addressed this knowledge gap by rearing Galaxias maculatus for 5 months at normal (15°C) and elevated (20°C) summer temperatures, with (hyperoxia) or without (normoxia) supplementary oxygen. Quantifying individual metabolic rate and GSA traits across body sizes encompassing most of the species' ontogeny, we found little evidence for a change in the proportion of GSA available per unit of metabolic rate (termed the S metric) and no improvements under hyperoxia. Importantly, at the elevated temperature where gill oxygen limitation should be most pronounced, the S metric did not change across body mass in either oxygen treatment (allometric exponents were no different from 0). These results indicate that the gills can grow in ways that support an individual's oxygen requirements, contrasting with the suggestion that size reductions of fish in response to climate warming are driven by an insurmountable geometric constraint at the gills. Read the free Plain Language Summary for this article on the Journal blog.

Impacts of temperature and turbidity on the gill physiology of darter species

Fish gills are complex organs that have direct contact with the environment and perform numerous functions including gas exchange and ion regulation. Determining if gill morphometry can change under different environmental conditions to maintain and/or improve gas exchange and ion regulation is important for understanding if gill plasticity can improve survival with increasing environmental change. We assessed gill morphology (gas exchange and ion regulation metrics), hematocrit and gill Na+/K+ ATPase activity of wild-captured blackside darter (Percina maculata), greenside darter (Etheostoma blennioides), and johnny darter (Etheostoma nigrum) at two temperatures (10 and 25 °C) and turbidity levels (8 and 94 NTU). Samples were collected August and October 2020 in the Grand River to assess temperature differences, and August 2020 in the Thames River to assess turbidity differences. Significant effects of temperature and/or turbidity only impacted ionocyte number, lamellae width, and hematocrit. An increase in temperature decreased ionocyte number while an increase in turbidity increased lamellae width. Hematocrit had a species-specific response for both temperature and turbidity. Findings suggest that the three darter species have limited plasticity in gill morphology, with no observed compensatory changes in hematocrit or Na+/K+ ATPase activity to maintain homeostasis under the different environmental conditions.

Effect of lipase and lipoxygenase on lipid metabolism and the formation of main volatile flavour compounds in fermented fish products: a review

SummaryLipid metabolism due to lipid hydrolysis and oxidation considerably contributes to the final product quality of fermented fish products and especially impacts its flavour. Lipase and lipoxygenase (LOX) are key enzymes involved in lipid metabolism. Endogenous lipases (lipase from fish muscle and adipose tissue) and/or exogenous lipases (lipase from microorganisms, the added lipase) catalyse the hydrolysis of lipids, producing numerous free fatty acids. LOX in fish gills and skin tissues plays an important role in lipid oxidation. During the catalysis by LOX, polyunsaturated fatty acids having cis, cis‐1,4‐pentadiene structure are oxidised, finally leading to the generation of flavour precursors or compounds such as alcohols, aldehydes, ketones, esters and acids. The addition of lipase effectively enhances the content of acidic components. Simultaneously, fermented fish products with a start culture capable of producing both lipase and LOX exhibit higher levels of flavour and aroma. In this process, the collaborative action of lipase and LOX generates a rich array of volatile flavour components. This review offers a comprehensive overview of the distinct functions and effects of both endogenous and exogenous lipase, along with LOX, in fermented fish products, as well as their roles in lipid metabolism. The study also explores their effects on the main volatile flavour compounds of fermented fish products. Moreover, the article discusses the prospects of applying lipase and LOX in fermented fish products, highlighting some limitations in current research and offering recommendations for future studies.

Bioconcentration Assessment of Three Cationic Surfactants in Permanent Fish Cell Lines.

Cationic surfactants are used in many industrial processes and in consumer products with concurrent release into the aquatic environment, where they may accumulate in aquatic organisms to regulatoryly relevant thresholds. Here, we aimed to better understand the bioconcentration behavior of three selected cationic surfactants, namely N,N-dimethyldecylamine (T10), N-methyldodecylamine (S12), and N,N,N-trimethyltetradecylammonium cation (Q14), in the cells of fish liver (RTL-W1) and gill (RTgill-W1) cell lines. We conducted full mass balances for bioconcentration tests with the cell cultures, in which the medium, the cell surface, the cells themselves, and the plastic compartment were sampled and quantified for each surfactant by HPLC MS/MS. Accumulation in/to cells correlated with the surfactants' alkyl chain lengths and their membrane lipid-water partitioning coefficient, DMLW. Cell-derived bioconcentration factors (BCF) of T10 and S12 were within a factor of 3.5 to in vivo BCF obtained from the literature, while the cell-derived BCF values for Q14 were >100 times higher than the in vivo BCF. From our experiments, rainbow trout cell lines appear as a suitable conservative in vitro screening method for bioconcentration assessment of cationic surfactants and are promising for further testing.

Cytotoxicity of Prymnesium parvum extracts and prymnesin analogs on epithelial fish gill cells RTgill-W1 and the human colon cell line HCEC-1CT.

Harmful algal blooms kill fish populations worldwide, as exemplified by the haptophyte microalga Prymnesiumparvum. The suspected causative agents are prymnesins, categorized as A-, B-, and C-types based on backbone carbon atoms. Impacts of P.parvum extracts and purified prymnesins were tested on the epithelial rainbow trout fish gill cell line RTgill-W1 and on the human colon epithelial cells HCEC-1CT. Cytotoxic potencies ranked A > C > B-type with concentrations spanning from low (A- and C-type) to middle (B-type) nM ranges. Although RTgill-W1 cells were about twofold more sensitive than HCEC-1CT, the cytotoxicity of prymnesins is not limited to fish gills. Both cell lines responded rapidly to prymnesins; with EC50 values for B-types in RTgill-W1 cells of 110 ± 11nM and 41.5 ± 0.6nM after incubations times of 3 and 24h. Results of fluorescence imaging and measured lytic effects suggest plasma membrane interactions. Postulating an osmotic imbalance as mechanisms of toxicity, incubations with prymnesins in media lacking either Cl-, Na+, or Ca2+ were performed. Cl- removal reduced morphometric rearrangements observed in RTgill-W1 and cytotoxicity in HCEC-1CT cells. Ca2+-free medium in RTgill-W1 cells exacerbated effects on the cell nuclei. Prymnesin composition of different P.parvum strains showed that analog composition within one type scarcely influenced the cytotoxic potential, while analog type potentially dictate potency. Overall, A-type prymnesins were the most potent ones in both cell lines followed by the C-types, and lastly B-types. Disturbance of Ca2+ and Cl- ionoregulation may be integral to prymnesin toxicity.

Effectiveness and safety of clove oil and common salt in the long-term transport of Cyprinus carpio

In this study, we aimed to evaluate the effectiveness and safety of clove essential oil (CEO) in combination with common salt during the long-term transport (24 h) of Cyprinus carpio. The experiment was conducted according to a completely randomized design with a 4 × 2 factorial arrangement, including four levels of CEO (0, 5, 10, and 15 mg L−1) and two levels of common salt (0 and 3 g L−1). Sampling was carried out before, immediately after, and 96 h after transport. CEO alone was not completely safe for C. carpio during transportation, as indicated by the increase in unionized ammonia in water and oxidative stress in fish gills and liver. Although common salt reduced water ammonia and fish stress responses (blood glucose), its use in isolation is not recommended, as it caused oxidative damage to the liver and gills. These effects had not been previously reported in the literature. However, the use of 5 mg L−1 CEO in combination with salt provided the best results both immediately after and 96 h after transport. In gills, there was a reduction in nitric oxide and carbonylated proteins and an increase in catalase activity at 96 h after transport. In the liver, there was a decrease in nitric oxide and oxidative damage (carbonylated proteins and malondialdehyde) immediately after transport, as well as a decrease in nitric oxide and an increase in glutathione-S-transferase activity at 96 h after transport. Thus, combined use of 5 mg L−1 CEO and 3 g L−1 common salt proved to be effective and safe, resulting in better maintenance of water quality (lower ammonia content) and redox status of the gills and liver in C. carpio during long-term transport.

Plant and yeast consortium for efficient remediation of dyes and effluents: a biochemical and toxicological study.

Textile effluent carries a range of dyes that may be recalcitrant and resistant to biodegradation. A unique consortium of the Fimbristylis dichotoma and Saccharomyces cerevisiae is exploited for the biodegradation of an azo dye Rubine GFL and actual textile effluent. This consortium enhances the rate of biodegradation of Rubine GFL and actual textile effluent with an excellent rate of biodegradation of 92% for Rubine GFL and 68% for actual textile effluent when compared to the individual one within 96 h. Speedy decolorization of Rubine GFL and actual textile effluent was observed due to the induction of oxido-reductive enzymes of the FD-SC consortium. Along with the significant reduction in the values of COD, BOD, ADMI, TSS, and TDS with 70, 64, 65, 41, and 52%, respectively, in experimental sets treated with FD-SC consortium. The biodegradation of Rubine GFL was confirmed with UV-Vis spectroscopy at the preliminary level, and then, metabolites formed after degradation were detected and identified by FTIR, HPLC, and GC-MS techniques. Also, decolorization of the dye was observed in the sections of the root cortex of Fimbristylis dichotoma. The toxicity of dye and metabolites formed after degradation was assessed by seed germination and bacterial count assay, where increased germination % and bacterial count from31×107CFUsto 92 × 107 CFUs reflect the nontoxic nature of metabolites. Furthermore, the nontoxic nature of metabolites was confirmed by fish toxicity on Cirrhinus mrigala showed normal structures of fish gills and liver in the groups treated with FD-SC consortium proving the better tactic for biodegradation of dyes and textile effluent.

Toxicological Effects of Synthesized Pyrazoline Derivative 4-(3-(4-Bromophenyl))- 5-(3,4-dimethoxyphenyl)-4,5-dihydro-1H-pyrazol-1-yl) Benzenesulfonamide, Compound B8 on Antioxidant Enzymes and Hematological Parameters of Rainbow Trout Alevins (Oncorhynchus mykiss)

The toxicological effects of a synthesized pyrazoline derivative 4-(3-(4-bromophenyl))- 5-(3,4-dimethoxyphenyl)-4,5-dihydro-1H-pyrazol-1-yl) benzene sulfonamide, compound B8, on rainbow trout (Oncorhynchus mykiss) were evaluated by following the activity of the antioxidant enzymes and the hematological parameters. Fish were exposed to variant doses (0.5, 1, and 2.5 mg L-1) of the compound B8 for 48 h. Antioxidant enzymes and activities were measured, and the obtained data were statistically analyzed. Our results showed that concentration at 1 mg L-1 significantly increased the malondialdehyde (MDA) levels (p < 0.05) in the liver and gills of rainbow trout (Oncorhynchus mykiss), while glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities were significantly decreased. The increase in MDA levels in the liver and gill could be related to tissue damage induced by oxidative stress after exposure to compound B8. Significant increases in white blood cell count (WBCs), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentrations (MCHC) were obtained (p < 0.05). Moreover, significant decreases were observed in erythrocyte numbers, hemoglobin concentrations, hematocrit levels, and platelet numbers (p < 0.05). The results showed that exposure to high doses (2.5 mg L-1) of the compound B8 caused oxidative stress in the liver and gills of fish and may lead to acute anemia.

Sequencing and multiple antimicrobial resistance of Pseudomonas fluorescens isolated from Nile tilapia fish in Egypt.

Pseudomonas fluorescens is one of the main causes of septicemic diseases among freshwater fish, causing severe economic losses and decreasing farm efficiency. Thus, this research was aimed to investigate the occurrence of P. fluorescens in Nile Tilapia (O. niloticus) fish in Egypt, gene sequencing of 16SrDNA gene, and antimicrobial susceptibility. P. fluorescens strains were detected in 32% (128\400) of apparently healthy (9%; 36\400) and diseased (23%; 92\400) Nile tilapia fish. The highest prevalence was observed in gills of fish, 31.3% followed by intestine 26.9%, liver 24.2%, and kidneys 17.6%. The PCR results for the 16SrDNA gene of P. fluorescens showed 16SrDNA gene in 30% of examined isolates. Moreover, Homogeny and a strong relationship between strains of P. fluorescens was confirmed using 16SrDNA sequences. Beside the responsibility of 16SrDNA gene on the virulence of P. fluorescens. The results of antimicrobial susceptibility tests revealed that all strains were resistant to piperacillin (100%), followed by ceftazidime (29.7%), and cefepime (25.8%). The strains of P. fluorescence were highly sensitive to cefotaxime (74.2%), followed by ceftriaxone and levofloxacin (70.3% each). Interestingly, 29.7% of strains of P. fluorescens were multiple antimicrobial-resistant (MAR).

Isolation and Identification of Pathogenic Bacteria from Commercially Marketed Fish in Wukari, North-Eastern Nigeria

Abstract Pathogenic bacteria that are part of the natural microflora can be found in aquaculture products. Microbial pathogens associated with fish can be transmitted to humans who consume or handle the fish. This study aimed to isolate human pathogenic bacteria present in the gills, intestine and skin of apparently healthy and spoil fishes. Tilapia (Oreochromisniloticus) and Cat fish (Clariaslazera) were collected from Wukari old market and Yam market of Wukari Nigeria. Bacteria were isolated from the fish gill, intestine and skin. The growth properties of distinct isolates on specific culture media were used to differentiate and characterize them. Pathogenic bacteria were recovered from various fish species that appeared with different features. The following human pathogenic bacteria were isolated; Escherichia coli and Staphylococcus aureus. The total bacteria count value ranges between 0.12 x 105 to 3.52 x 105 for the tilapia fish and 0.12 x 105 to 3.96 x 105 cfu/ml for cat fish. The identification revealed that Staphylococcus aureus and Escherichia coli was the most abundant pathogenic bacteria and also present in the initial water samples collected. Presence of Staphylococcus aureus and Eshcherichia coli is attributed to contamination of the fish samples by man through handling and processing. These enteric bacteria in fish serve as indicator organisms of faecal contamination and or water pollution. Their presence also represents a potential hazard to humans’ life. The isolates were higher from Yam market samples compared to Wukari old market.

Organoleptic Testing and Histopathological Examination of Gills of Thunnus Sp. And Sardinella lemuru as Raw Materials for Gill Chips

Utilization of tuna (Thunnus sp.) and lemuru (Sardinella lemuru) in the fishing industry has not been developed optimally and still produces by-products. Fish gills are one of the by-products of fisheries that contain protein, fat, water, ash, and carbohydrates, reaching 15.532%, 1.942%, 69.880%, 10.490%, and 2.156%, respectively. In_Sang Epic is food that utilizes fish gills as its raw material. For consumer safety, the product should undergo an organoleptic test under the SNI 2729:2013 score sheet method. The histopathological examination process which included fixation, tissue processing and embedding, sectioning, staining, mounting, and observation with a microscope. The results of organoleptic test indicated that the gills of tuna and lemuru had average values of 8.3 and 7.8, respectively, which is fulfilling the standards of fresh fish according to SNI 2729:2013. Meanwhile, the result of histopathological from gills of tuna samples were suspected of having necrosis, as characterized by hypertrophy of megakaryolysis, and that those of lemuru were suspected of having autolysis, as characterized by rupture. However, the gills of both kinds of fish were still suitable for use as raw materials of In_Sang Epic because the samples were ineligible to undergo histopathological testing.

Exploring the Potential of Isalo Scorpion Cytotoxic Peptide in Enhancing Gill Barrier Function and Immunity in Grass Carp (Ctenopharyngodon idella) Infected with Flavobacterium columnare

The objective of this research was to investigate how dietary antimicrobial peptides (AMP), namely, Isalo scorpion cytotoxic peptide (IsCT), affect the gill physical barrier function and immune function of grass carp challenged with Flavobacterium columnare (F. columnare). Five hundred forty grass carp were randomly allocated to six groups and fed to varying levels of IsCT in the diet (0, 0.6, 1.2, 1.8, 2.4, and 3.0 mg/kg diet) for a duration of 60 days. Afterward, the grass carps faced a challenge from F. columnare. The results revealed that the use of optimal IsCT dramatically mitigated gill damage in grass carp that were infected with F. columnare. Additionally, IsCT exhibited a notable enhancement in gill antioxidant capabilities, as evidenced by a significant reduction in ROS, MDA, and PC levels, an elevation in antioxidant enzyme activities, and an upregulation of antioxidant‐related genes and Nrf2 mRNA levels. Conversely, the expression of Keap1a and Keap1b mRNA was decreased. Besides, IsCT exhibited its capability to inhibit apoptosis via downregulating the mRNA levels of caspase-2, caspase-3, caspase-7, caspase-8, caspase-9, Apaf1, Fasl, Bax, and JNK while concurrently increasing the mRNA levels of Bcl-2, Mcl-1, and IAP in fish gills. Additionally, IsCT promoted the integrity of tight junction barrier by increasing the gene expression of claudin-b, claudin-c, claudin-3c, ZO-1, ZO-2b, occludin, and JAM while suppressing MLCK signaling. Additionally, optimal dietary IsCT improved antibacterial ability, as evidenced by heightened LZ, ACP activities, and elevated levels of C3, C4, and IgM. Additionally, there was an upregulation in β-defensin-1, LEAP-2A, LEAP-2B, hepcidin, and mucin-2 mRNA expression in the gills. Simultaneously, the inclusion of optimal dietary IsCT in the diet resulted in improved gill immunity barriers through the reduction of proinflammatory cytokine mRNA levels and the increase in the expression of anti‐inflammatory cytokine mRNA levels. This was partly facilitated by the IκBa/NF‐κB p65 signaling pathway and TOR/S6K1 signaling pathways in the gills of grass carp. Therefore, supplementing the diet with IsCT has potential advantages in enhancing gill health by improved physical barriers and immunity in grass carp. Based on LZ activity and against lipid peroxidation, optimum IsCT concentrations in on‐growing grass carp (136.88 ± 0.72 g) were found to be 1.68 and 1.54 mg/kg diet, respectively.

Host-specific monogeneans parasitizing freshwater fish: The ecology and evolution of host-parasite associations.

Monogenea (Platyhelminthes), mainly gill and fin ectoparasites of fish, are often recognized as host specific and morphologically and ecologically diverse. These parasites exhibit high species diversity at the level of host species or individual fish specimens. Using case studies, especially those widely performed in Dactylogyrus parasitizing cyprinoid fish, this article presents current knowledge on the ecology and evolution of congeneric gill monogeneans. The important aspects of the ecology of congeneric monogeneans are highlighted, in particular: host specificity expressed at several host levels (from strict specificity to phylogenetic specificity), microhabitat specificity expressed by restricted positions on fish gills to facilitate intraspecific mating, and the link between microhabitat preference and morphological adaptation (i.e., sclerotized structures of the haptor) or reproductive isolation. From the evolutionary perspective, this study focused on the processes of the speciation and diversification of congeneric monogeneans, highlighting the role of host switch as the most prominent coevolutionary event, accompanied in some cases mostly by intrahost speciation or cospeciation, as revealed by cophylogenetic studies. Here, important knowledge on evolutionary patterns of host specificity, microhabitat specificity, and morphological adaptation is presented. Host-specific monogeneans may represent an important tool for studying the historical biogeography of their hosts. Specifically, in the case of freshwater fish hosts exhibiting disjunctive distribution, they reflect both historical and contemporary contacts. The role of host-specific congeneric monogeneans in revealing historical intercontinental and intracontinental contacts between freshwater fish is highlighted. Finally, the importance of the role of genetic coadaptation, limiting the presence of host-specific monogeneans in hybrid fish, is emphasized.

Current state of juvenile roach (Rutilus rutilus caspicus)

Fluctuations in water temperature in the Northern Caspian Sea, especially in the shallow zone, are mainly due to fluctuations in air temperature and during the trawling period, in the fall, the water temperature at observation stations showed a decrease in water temperature, which caused the formation of dense aggregations in juvenile roach. To study the nutritional status of juvenile fish living in the Kazakh part of the Caspian Sea, material was selected from different depths of the sea from trawl catches during comprehensive research in the fall of 2022. In the course of studies conducted to assess nutrition using quantitative and qualitative indicators, it was determined that the nutritional spectrum of juvenile roach in the water Caspian Sea is represented mainly by the same bottom organisms with a dominance of crustaceans, with their preference for bivalves, which give a good growth rate. A parasitological study of juvenile roach showed the absence of pathogen circulation in the ecosystem of this reservoir. Based on the results of pathomorphological studies of fish gills, it was found that fragmentary hyperplasia is caused by the presence of protozoal invasion rather than by the influence of environmental factors.

Slippery hydrogel surface on PTFE hollow fiber membranes for sustainable emulsion separation.

Establishing an efficient and sustainable membrane module is of great significance for practical oil/water emulsion separation. Superwetting membranes have been extensively studied but cannot meet long lasting separation owing to inevitable membrane fouling. Herein, we constructed a hydrogel-mediated slippery surface on polytetrafluoroethylene (PTFE) hollow fibers and then designed a flexible and swing hollow fiber membrane module inspired by fish gill respiration, which achieved sustainable emulsion separation. A vinyl silane-crosslinked polyvinylpyrrolidone (PVP) hydrogel was interpenetrated with nano-fibrils of the PTFE hollow fibers, thus facilitating fast water permeance while resisting oil intrusion. Liquid-like polydimethylsiloxane (PDMS) brushes were then grafted to promote oil aggregation-release from the membrane surface. Owing to the heterogeneous surface and gill-like structure, the designed PTFE hollow fiber membrane module could separate emulsion in a long-term filtration process, maintaining a high water permeability of 500 L m-2 h-1 bar-1 with a separation efficiency of over 99.9% for 5000 min. This novel technique shows its great potential to realize practical emulsion separation by solving the persistent problem of membrane fouling and permeance decay.

Influence of Cypermethrin and Chelating Properties of 2r, 4c-Bis(p-Methoxyphenyl)-7c-(t- Butyl)-3-Azabicyclo (3.3.1) Nonan-9-One Oxime on Ultra structure of Gill and liver

The toxic effects of cypermethrin on the ultrastructure of the gills and liver of the freshwater fish Labeo rohita's gills and liver were studied. The purpose was to see if pesticide concentrations and exposure time influenced the degree and nature of ultrascture alterations in exposed fish's gills and liver. Selected fish were exposed to a mixture of 5% concentrations of the LC50 of cypermethrin for both short and long periods of time. The gills and liver of specimens subjected to 120 hours experienced similar hyper structural alterations. Clearly indicating a harmful response to both pesticide doses. These ultra structural changes included lesions such as oedema in the primary and secondary lamellae, fusion of neighbouring secondary lamellae, and epithelial layer lifting, hyalinization, hepatocyte vacuolation, cellular swelling, and blood vessel congestion. The amount of the exposure period, however, had an effect on the degree of these hyper structural alterations.

Comparison of Ectoparasites infestation for fresh and saltwater Fishes from Euphrates, and Razzaza Lake, Iraq

Parasitic infestations represent one of the main challenges to fresh water and marine fish all areas of the world. The infections are commonly found on the skin and gills of fish and can cause dangerous problems, as mortality, in heavily parasitized infections. This study was conducted to detect of ectoparasite types in Fishes, 200 of Coptodon zillii from Euphrates and 120 Cyprinus carpio from Razzaza Lake, were used for this study in aquatic environment. The specimens were purchased at 2022 in different periods from market and selected. The collection of fish using gill nets. The collected of fish samples was carried out in lab and used macroscopic inspection, gross viscera, microscopic exam-wet mount of fins, skin, gills and eyes. The results of the both infected fishes revealed the presence of several clinical signs. The prevalence was 65.6%, in Coptodon zillii was 30% and Cyprinus carpio was 100%. Indeed, we observed the appearance of necrotic areas, ulcerations and hemorrhage on the gills. On others body parts, we found Protozoa and Monogeneans parasites. The identification of ectoparasite were obtained in fins, skin, and gills and no infection in eyes. There are 4 types of ectoparasites were infect to Coptodon zillii, that is Trichodina sp., Ichthyophthirius multifiliis sp., Dactylogyrus sp., and Gyrodactylus sp. While, Cyprinus carpio that is I. multifiliis and Gyrodactylus sp. Significantly of results at P≤0.05 of fish type with weight and long but not significant for genders in both types. In future studies should be focusing on modern tools to identification of parasites species in different environments.