Search

Water resource pollution is a significant issue that is only becoming worse even with the appropriate laws in place. Because effluent contaminants tend to accumulate in aquatic species, genotoxic researches on these pollutants are crucial. Therefore, using aquatic organisms to measure Genotoxicity is a highly helpful environmental monitoring technique. River Ami is a significant body of water in Maghar Sant Kabir Nagar, Uttar Pradesh, India that was contaminated by many industrial sources' untreated effluents. The current study set out to assess the genotoxic effects of these effluents on Channa punctatus fish as well as their toxic impacts on water quality. The research of Genotoxicity (the impact of bleached effluent on fish micronuclei) was conducted using the micronuclei. Fish treated with bleached effluent showed a significant (p<0.05) increase in the quantity of micronuclei compared to fish that were directly collected from the Aami River. Temperature, pH, DO, BOD, COD, TSS, and TDS are among the physico-chemical characteristics of a body of water that are assessed seasonally. All of these metrics were significantly higher than the Central Pollution Control Board of India's suggested tolerance limit. [ABSTRACT FROM AUTHOR]

Dichlorvos (2, 2-dichlorovinyl dimethyl phosphate) is an organophosphate compound used to control household and public health. It is effective against mushroom flies, aphids, spiders, caterpillars and white flies in greenhouse and vegetable crops. The cellular detoxification processes may be different and represent a more general and well-known situation of oxidative stress due to the production of free radicals. The present investigation was aimed at studying the Dichlorvos in fish Channa punctatus. The value of LC50 of Dichlorvos was determined as 1.26 ppm for Channa punctatus. It was found that after chronic exposure damage value was highest at all concentrations in tissues. [ABSTRACT FROM AUTHOR]

Copper is one of the most toxic metals to fish and causes cytotoxic, mutagenic and carcinogenic effects. The accumulation of copper in an aquatic environment directly impacts man and the aquatic ecosystem. The present study aimed to determine the effect of copper sulphate (CuSO4) accumulation on the induction of micronuclei in blood and histological changes in kidney and liver of the fish Channa punctatus. The test chemical LC50 was determined after 96 hours during the first experiment. Later in the second experiment, the test animal was exposed to three sub-lethal concentrations of CuSO4 [0.1 mg/l (96 h-LC50/40), 0.2 mg/l (96 h-LC50/20) and 0.4 mg/l (96 h-LC50/10)]. Physico chemical parameters of the test medium, such as pH, temperature, hardness, alkalinity, and dissolved oxygen, were observed throughout the experiment, and all values were within the ranges necessary for the fish's survival. At intervals of 7, 14, 21, and 28 days, the control (without any test chemical) and copper sulphate exposed Groups' blood, liver, kidney, and gill tissues were taken to evaluate changes in genotoxic and histological parameters. Micronuclei (MN) induction and nuclear abnormalities (NAs) were observed at regular intervals. After 28 days, the MN frequency in Groups 1, 2, 3, and 4 was 0.78±0.006, 8.40±0.052, 10.37±0.098 and 10.90±0.024 respectively. A significant (P< 0.05) rise in MN frequencies and NAs indicated fish erythrocytes' DNA damage. Histological analysis of the liver, kidney, and gills revealed serious tissue injury such as necrosis, vacuolization, and degeneration after 28 days in the exposed Groups. The present study observed changes due to genotoxicity and histology, giving the most comprehensive understanding of CuSO4 stress on the fish C. punctatus and its risks to human health. [ABSTRACT FROM AUTHOR]

Acute and chronic exposure of heavy metals exerts detrimental effect at the cellular level and is a rising global concern. The pollutants once introduced in the water bodies, subsequently enters the food chain, and poses risks not only to the aquatic organisms, but to the human consumers as well. Therefore, understanding the toxicological level of these metals is vital for assessing the severity of potential risks. The study aimed to conduct a comparative analysis of the acute toxicity of mercury and cadmium on Channa punctatus through a 96-hour bioassay. It was carried out in a semi-static laboratory condition following the standard guidelines. The behavioural, and mortality response was recorded at the 24, 48, 72, and 96 h of exposure duration for both toxicants. The results demonstrated distinct differences in toxicity levels between mercury and cadmium. The 96h-LC50 value for cadmium was measured at 6.19 mg/l, while for mercury, it was significantly lower at 0.44 mg/l. It was revealed that even the trace concentration of metals can induce toxicity, if given for a prolonged period of time. Furthermore, the study observed heightened toxicity of mercury, exerting adverse effects at lower concentrations compared to cadmium within the same exposure duration. [ABSTRACT FROM AUTHOR]

Fish and other members of aquatic habitats are in constant contact with the microbes that trigger their immune system to produce immune components along with mucus. Compounds like lysozymes, proteases, lectins and peroxidase were reported in many studies. The study aims to identify and characterize the immune components present in the epidermal mucus of Channa punctatus. For this, antibacterial and antifungal efficacy was tested first using agar well diffusion assay and MIC was measured. Maximum activity against bacteria’s E. coli, S. aureus and Fungus H. gramineum was observed. FESEM analysis was performed to reveal the mechanism of the antimicrobial activity. Physico–chemical stability of mucus was also checked by exposing to various parameters such as (temperature, pH, proteases and surfactants). Precipitated proteins of mucus were separated using 12% SDS-PAGE assay. The band was digested using trypsin digestion and digested peptides were subjected to LCMSMS analysis for identification and on characterization using MASCOT servers 2 proteins (Hemoglobin subunit beta-A-globin chain and Galactose specific lectins nattectin) with number of fragmented unique peptides were obtained. Insilico predictions of antibacterial, antifungal, antiviral and anticancerous properties of peptides were also determined to support the role of mucus in microbial defense and therapeutical applications using the servers AMPfun, DBAASP and APD3. [ABSTRACT FROM AUTHOR]

Genetic variation in a species increases the capability of an organism to get adapted to a changing environment, which is important for survival of the species. Genetic variations between Channa punctatus fish collected from three water sources of Manipur were studied and examined by using randomly amplified polymorphic DNA (RAPD). Twenty primers were used during the study, out of which only five primers were used for genetic diversity studies. Based on the genetic identity, clustering analysis showed the genetic relationship of the three populations through a dendrogram. It shows that the Pallel sample is genetically closer to the Yaral Lake C. punctatus fish rather than from the Pumlen Lake. The existence of variability among the populations and also within the population is important for their ability to survive and in responding to environmental changes. The dendrogram obtained for three populations also differentiated the three populations of C. punctatus showing the existence of genetic variability exists between them. [ABSTRACT FROM AUTHOR]

The current investigation focus to analyse the effects of starvation on activities of Alanine amino transferase (ALT) and protein contents in Channa punctatus after 3, 6, 9, 12 and 15 days of starvation respectively. The results indicated that, there was significant increase in alanine transferase (ALT) activities from 3rd day of starvation in blood and liver whereas in muscle it was observed on 15th day of starvation. In case of aspartate aminotransferase (AST), significant increase in activities was observed from 3rd day in blood, 6th day in liver and 12th day in muscle to that of control. However, in comparison to control, the protein contents of liver in the starved groups declined by 1.01, 1.06, 1.10, 1.13 and 1.17 folds after 3, 6, 9, 12 and 15 days of starvation periods respectively. The results specifies drastic changes in ALT, AST activities and protein contents in C. punctatus during short term starvation. [ABSTRACT FROM AUTHOR]

A new microsporidian subspecies was found to infect Channa punctatus that were collected from the river Gomti in Lucknow. This parasite invades the liver, gills and kidney of the fish by forming cyst (xenoma). The prevalence of infection was 58.33%. A 1360 bp long sequence of small subunit of rRNA gene (16S) was obtained after sequencing and submitted in GenBank database within the accession number OP537923. To know about the phylogenetic description of the present sequence, molecular analysis based on small subunit of 16S rRNA gene was accomplished using maximum parsimony method. Phylogenetic analysis disclosed that this species showed highest similarity with the genus, Ovipleistophora having differences in 13 positions in the nucleotide sequences. So, the present species considered as a subspecies within the genera Ovipleistophora herein named as Ovipleistophora ovariae SW02. [ABSTRACT FROM AUTHOR]

Annual rhythms in immune function are the reflection of a crucial physiological strategy to deal with environmental stressors. The fish are pivotal animal models to study the annual rhythm and to understand the evolution of the vertebrate biological system. The current research was planned to assess the annual changes in the innate immune functions of immune cells in a teleost, Channa punctatus. Head kidney and splenic macrophage phagocytosis, superoxide generation, and nitrite release were evaluated to assess innate immunity. Cell-mediated immunity was measured through head kidney and splenic lymphocyte proliferation in presence of mitogens. The superoxide anion generation by the cells of head kidney and spleen was maximum in October. A bimodal pattern in nitrite production was observed with the first peak in November and the second in March. Cosinor analysis revealed a statistically significant annual rhythm in nitrite production. Similarly, phagocytosis and lymphocyte proliferation also showed statistically significant annual rhythms. It was concluded that animals maintain an optimum immune response in seasonally changing environments. Elevated immunity during certain times of the year might assist animals deal with seasonal environmental stressors. Further research may be focused upon measuring survival rate and reproductive success after season induced elevated immunity.

Gonadotropin inhibitory hormone belonging to the RFamide peptide family, a hypothalamic neuropeptide, regulates Hypothalamus-pituitary–gonadal (HPG) axis and inhibits gonadal development. GnIH polypeptide precursor has an Arg-Phe-NH2 (RFamide) motif at the C-terminal, which has LPXRF (X = Q or L) domain. The actions of GnIH are mediated through G-protein coupled receptors and upto three receptors have been characterized in many teleosts. GnIH exerts its inhibitory effect on the HPG axis through direct interaction with GnRH and Kisspeptin neurons in the brain and acts directly on the pituitary gonadotrophs. To decipher the role of GnIH in Indian freshwater murrel, Channa punctatus, we sequenced the cDNA encoding GnIH and its two receptors. The identified GnIH mRNA encodes three RFamide peptides having -MPMRF, -MPQRF, and -LPQRFamide motifs. In silico analysis of the amino acid sequence of GnIH exhibits its molecular and functional properties and the protein–protein interaction with significant factors regulating the HPG axis. The 3-D structure of GnIH and its receptors, provides more relevant information about the active residues of these proteins which might be involved in their functioning and interaction with other proteins. Molecular dynamic simulation of GnIH protein has provided more insight into its dynamic behavior. The expression of GnIH and its receptors, shows an inverse correlation with gonadal development during the annual reproductive cycle. [ABSTRACT FROM AUTHOR]

The use of pesticides and other chemicals in agriculture may eventually interact with the aquatic environment, accumulate in the food chain, and result in major ecological and health issues. Cypermethrin, a synthetic broad-spectrum pyrethroid insecticide, commonly used to manage a variety of insect pests in homes, industries, and agricultural fields. Cypermethrin enters into the aquatic system through agriculture run-off water. The presence of various toxicants in over permissible amounts has led to widespread fish mortality. In the present article, Channa punctatus, a freshwater fish, were treated separately to different concentrations of cypermethrin for a period of 24 hours, 48 hours, 72 hours, and 96 hours. The median lethal concentration (LC50) of cypermethrin for fish was determine by probit analysis. Fish exposed to Cypermethrin appeared hyperactive, irritated, visited the surface more frequently and showed the loss of schooling habit. The 96-h LC50 value for Channa punctatus, was estimated as 0.178 mg/L. Acute toxicity assessment offers first-hand knowledge to monitor and track the rigours of aquatic ecosystems as well as pollutants. [ABSTRACT FROM AUTHOR]

Snakehead fishes are widely consumed throughout South East Asia, China and India because of their good taste in meat and high nutrient values such as the presence of prostaglandins, thromboxane, and Omega-6 fatty acid. Parasites are one of the most serious limiting factors in aquaculture. Parasite Pallisentis were commonly found in the freshwater perciform fish family Channidae. In this present study, fifteen hundred seventy specimens of Channa punctatus were examined for parasitic Pallisentis fauna, and out of this thirty-seven specimens were found to be infected with Acanthocephala. All parasitic infections observed and recorded in the present study were restricted to the intestine of the fish. The male specimens show a higher prevalence of about 69.44% than the female specimens only 63.15. The intensity of infection in males is 3.52 and that of females is 6.08. The fish specimen with the intermediate weight group shows the highest (66.7%) prevalence of infestation. However, further study is still required to reveal many enclosed parasitic infections of fishes and their causation, particularly in this region with a high diversity of fishes. Parasitic infection constitutes significant economic losses in fish production. Parasites are one of the most serious limiting factors in aquaculture. Therefore, the present investigation has been undertaken to sort out the population dynamics of Pallisentis (Acanthocephala), in relation to host sex from freshwater fishes, Channa of Sultanpur region. [ABSTRACT FROM AUTHOR]

Synthetic pyrethroids are applied in agricultural fields for the control of pests. However, these pyrethroids pose a serious threat to other non-targeted organisms such as fish. Thus the present study is aimed to evaluate the acute toxicity of a pyrethroid, Bifenthrin 10% EC on some histopathological and behavioral activity of Channa punctatus. Channa punctatus was exposed to three sublethal dose concentrations of 1, 3 and 6 µl/l of bifenthrin 10% EC (w/w). The LC50 value of Bifenthrin 10% EC after 24 hours of treatment was found to be 3.784 µl/l. Changes in the swimming rate, surface activity and balancing behavior were found to be greatly affected in dose-dependent concentrations. Bifenthrin treatment also showed an adverse effect on the gills, liver, intestine and ovary of C. punctatus. In treated samples, gills showed blood congestion and damaged gill filament and liver showed deformations such as hemorrhage, vacuolation and certain pyknotic regions. Bifenthrin also affected the intestinal lining a ruptured serosa layer, damaged or degenerated villi, etc. along with it ovary was also severely affected and developed abnormalities such as reduced/damaged oocyte, stromal vacuolation. Our result demonstrates that Bifenthrin even at 1 µl/l affects the behavior and histology of vital organs in C. punctatus. [ABSTRACT FROM AUTHOR]

To find out the dietary leucine requirement of fingerling Channa punctatus (5.24 ± 0.07 g), six purified experimental diets (45% CP and 14.73 kJ/g DE) with various leucine concentrations (0.5, 1.0,1.5, 2.0, 2.5 and 3.0% diet) were fed to apparent satiation to triplicate groups for 12 weeks (714/02/a/CPCSEA). Absolute weight gain, specific growth rate, feed conversion ratio, protein efficiency ratio, protein and leucine retention efficiency, and RNA/DNA ratio improved up to 2.0% leucine in the diet. Carcass protein and fat increased significantly with increasing leucine levels up to a 2.0% dry diet. Moisture content showed a reverse pattern. Red blood corpuscles hemoglobin and hematocrit increased with incremental levels of leucine up to 2.0% diet. Significant changes were also noted in serum total protein, superoxide dismutase, aspartate aminotransferase, alanine aminotransferase, and lysozyme activity. Serum protein, superoxide dismutase and lysozyme activity were positively correlated with increasing leucine levels up to 2.0% diet, whereas aspartate aminotransferase and alanine aminotransferase showed the opposite trend. Based on the quadratic regression analysis of absolute weight gain, specific growth rate, feed conversion ratio, protein, and leucine retention efficiency, inclusion of 2.0% leucine is recommended for optimum growth of fingerling C. punctatus. [ABSTRACT FROM AUTHOR]

Hematological measures have been acknowledged as useful instruments for assessing changes in water quality and other relevant environmental factors that may have an impact on fish health. In this study, the effects of heavy metal content on the hematological parameters of the fish Channa punctatus from the freshwater of Gomti river Lucknow were assessed. The amounts of zinc (Zn), copper (Cu) and lead (Pb) in the river’s water and sediments were measured. The exposed fish’s blood parameters were also checked for any hematological changes at the same time. The findings showed that the river water and sediments had significantly different metal contents (p <0.05). Cu was the metal with the highest concentration (mg/l), followed by Zn and Pb was not found in any sample. Fish were found to have blood characteristics that were different from normal, including blood cell count (red and white blood cells), hemoglobin, hematocrit, mean cell hemoglobin concentration, mean cell volume and mean cell hemoglobin (p <0.05). This study’s findings concluded that Cu and Zn contaminated river water and had a negative impact on fish health. The distribution of heavy metals and the approximate composition of significant edible fish from this freshwater river in India are also being reported for the first time in this paper. [ABSTRACT FROM AUTHOR]

The genus Pallisentis has been mostly found among the freshwater fishes of Channidae family. Pallisentis ophiocephali is characterized with some unique characters of proboscis, hooks, and spines. However, initial description is a little sketchy and yet not updated. The present study communicates the detail morphology of an acanthocephalan species obtained from two host fishes of Channidae family--Channa striatus and Channa punctatus--during a one-year survey from different places of Hooghly District, West Bengal. The parasite is examined under light microscope as well as under scanning electron microscope. Unique four hook circles with different sizes, collar, and trunk spines, male and female genital organs are described for taxonomic study. Scanning electron microscopic study also provides the detailed information about the surface topography including longitudinal muscle, retractor muscles, and posterior ends. Comparing the studied specimen with other closely related species, the present acanthocephalan specimen has been identified as P. ophiocephali from Channa striatus. The retractable nature of proboscis has also been studied from the live specimens with the help of light microscope. [ABSTRACT FROM AUTHOR]

This investigation was conducted to compare the electrophoretetic banding patterns of esterase isozyme in the gill, liver, and brain tissues of the freshwater fish Channa punctatus (Bloch) at 24 hours, 48 hours, 72 hours, and 96 hours after exposure to Malathion (an Organophosphate) to those at the control group. Quantitative analysis of the esterase isozymes was performed using 7.5 native polyacrylamide gel electrophoresis (PAGE) stained with -naphthyl acetate as substrate. The relative mobilities of three esterase Isozyme bands in gill, liver, and brain tissue were determined to be 0.60.05, 0.40.05, and 0.30.05, respectively; these bands were designated Est-1, Est-2, and Est-3, respectively. Control samples from the gill, liver, and brain all had all three esterase bands. Both Est-2 and Est-3 Esterase Isozyme bands in gill and liver tissue were eliminated when fish were subjected to Malathion (an Organophosphate) for 72 and 96 hours, respectively. Malathion induced greater damage in Est-1 and Est-3 brain tissue than in Est-2. [ABSTRACT FROM AUTHOR]

In the recent years, Fluoride has emerged as one of the most harmful pollutants in the world and its presence has been shown to negatively impact the quality of groundwater in many countries. According to World Health Organization (WHO), when its concentration exceeds 1.5 mg/L limit, it may cause threats to the health. Exposure to high concentrations of fluoride has been known to have deleterious effects on the biological system of human as well as other animals. Based on this background, a study has been conducted to show the effects of sodium fluoride induced toxicity in the freshwater fish Channa punctatus (Bloch.). The fishes were exposed to sublethal doses of 25 ppm and 50 ppm of sodium fluoride for a period of 3 and 7 days. The damaging effects of sodium fluoride were manifested in the morphological, behavioural, haematological, biochemical and histological parameters of the fishes. The fishes were then further exposed to 100 mg/L of methanolic leaf extracts of tulsi, tea and a combined formulation of the two extracts to investigate the ameliorative properties in the revival of fluoride toxicity in the fishes. However, the results showed that the impact of toxicity caused by exposure to 25 ppm was much less pronounced as compared to 50 ppm of sodium fluoride. These effects were revealed to be effectively reduced by the addition of the plant extracts. Both the selected plant extracts showed positive results. However, their combined formula revealed the highest level of effectiveness in the remedial activity of fluoride induced toxicity. [ABSTRACT FROM AUTHOR]

Dichlorvos (2, 2-dichlorovinyl dimethyl phosphate) is an organophosphate compound used to control household and public health. It is effective against mushroom flies, aphids, spider, caterpillars and white flies in greenhouse and vegetable crops. The cellular toxification processes may be different represent a more general and well known situation of oxidative stress due to the production of free-radicals. Present investigation was aimed to study of the Dichlorvos in fish Channa punctatus. Value of LC50 of Dichlorvos was determined as 1.26 ppm for C. punctatus. It was found that after chronic exposure damage value was highest at all concentrations in histopathological tissues. [ABSTRACT FROM AUTHOR]

The river Shivna accommodates large scale of agricultural activities, where large quantities of pesticides are applied. To assess the biological impact of pesticide residues that are continuously entering in the water body, biomarkers are common approach in bio-monitoring study as early warning signals to pollutants Shah and Parveen (2022). In the present study analyses of gill histopathological parameters were determined in Channa punctatus. Histopathological biomarkers of toxicity in fish organs are useful indicator of environmental pollution (Bhandare et al, 2019). The fishes Channa punctatus were exposed to lethal concentration at 96 hrs LC50 and sub lethal concentratins at (1/5, 1/10 and 1/15 ppm) of dimethoate for 30 days. [ABSTRACT FROM AUTHOR]

The kidney and liver, tissues of Channa punctate were all destroyed after administration to sub-lethal quantities of parathion according to all histological findings. Histopathological changes in the kidney, liver, such as those seen in this research and prior research, can cause serious physiological difficulties in fish, eventually resulting in death. To summaries, the results of the current histological research show a direct link between pesticides exposure with histopathological problems across several tissues. [ABSTRACT FROM AUTHOR]

The crucial phase I xenobiotic metabolising enzyme cytochrome P450 (CYP 450) has a variety of isoforms and a wide range of substrate specificities. While the roles of mammalian CYP 450 are well established, those of nonmammalian species are much less defined. These roles are frequently extrapolated from mammalian data and assumed to be similar across vertebrate species. In the present study, three air breathing fish species, Channa punctatus, Heteropneustes fossilis and Clarias batrachus were injected intraperitoneally (IP) with 50 mg/kg β-naphthoflavone (β-NF) and its effects on hepatic CYP 450 system were evaluated. β-NF treatment resulted in significant increase (p<0.01) in CYP 450 content and CYP1A mediated EROD (Ethoxyresorufin O-deethylase) activity in all three treated fish groups compared to control. CYP2B mediated N,N-dimethylaniline demethylase activity and CYP2E1 mediated aniline hydroxylase activity showed no response suggesting insensitivity to β-NF treatment. All three fish species showed an increase in CYP3A4 mediated erythromycin N-demethylase activity, but only H. fossilis displayed a significant difference (p<0.05). Of all the activities investigated, EROD activity mediated by CYP1A responded towards β-NF treatment the best and could serve as a sensitive biomarker to gauge the effects of chemical pollutants in the aquatic environment. [ABSTRACT FROM AUTHOR]

The influence of different stocking density on the rearing of fish, Channa punctatus in terms of weight gain (grams) and survival ratio (%) was investigated. Present trial was conducted for a period of 90 days in cemented tanks at University of Sindh, Jamshoro, Pakistan. Different stocking densities were determined such as 10, 15, and 20 fish/m2were selected and placed in different treatments (I-III) with two replicates Fish were fed all parts of chicken (APC) with 10% of their body weight. The results of the growth trial indicated moderate variation among the treatments that, 10 fish/m2in T-I exhibited maximum growth (64.6 g) with 100% survival ratio as compared to other treatment (II and III), 15 fish/m2 (35.0 g with 90% survival) and 20 fish/m2 (16.4 g with 80% survival), respectively. The water quality parameters were monitored on fortnightly basis, such as temperature values were found within optimal range of 26.8 to 30.6oC, pH (7.3 to 7.5), oxygen (4.0 to 4.8mg/l), alkalinity (149 to 180mh/l), nitrate (0.17 to 0.18mg/l) and ammonia from 0.35 to 0.55ug/dLumol/litre. Theresults of the current study concluded that Channa punctatus have a preference to living in a small community than large schooling and could be reared 10/fish/m2 was found to be suitable density for growth and survival in cemented cisterns. Present study plays an important role for culturing and rearing of native snakehead species. [ABSTRACT FROM AUTHOR]

Parasites belonging to the trematode family Clinostomidae have a global distribution. Freshwater fish in Bangladesh frequently serve as hosts for different clinostomid species. During the metacercaria stage, the digenetic trematode Euclinostomum heterostomum exhibits a specific preference for Channidae species, where it undergoes encystment within the liver, kidneys, and muscles of these hosts. The study aimed to identify E. heterostomum in Channa punctata through combined morphological and molecular analysis. Light and scanning electron microscopy were conducted to investigate the morphological characteristics of the species. The histological examination of the infected liver tissue revealed the presence of encysted flukes, inflammatory leukocyte infiltrates, and degeneration and loosening of hepatic tissue. In molecular analysis, the generated internal transcribed spacer 1 (ITS1), 5.8S ribosomal DNA and ITS2 regions sequence (GenBank accession no: OR591452) of 830 bp showed 100% identity with Euclinostomum heterostomum identified in India (MT785786). The phylogenetic reconstruction provided substantial evidence of genetic similarities (0-1% genetic distance) among different isolates of the genus Euclinostomum, suggesting that there is a shared heritage., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Background: Blotched snakehead (Channa maculata) displays significant sexual dimorphism, with males exhibiting faster growth rates and larger body sizes compared to females. The cultivation of the all-male population of snakeheads holds substantial economic and ecological value. Nonetheless, the intricate processes governing the development of bipotential gonads into either testis or ovary in C. maculata remain inadequately elucidated. Therefore, it is necessary to determine the critical time window of sex differentiation in C. maculata, providing a theoretical basis for sex control in production practices., Methods: The body length and weight of male and female C. maculata were measured at different developmental stages to reveal when sexual dimorphism in growth initially appears. Histological observations and spatiotemporal comparative transcriptome analyses were performed on ovaries and testes across various developmental stages to determine the crucial time windows for sex differentiation in each sex and the sex-related genes. Additionally, qPCR and MG2C were utilized to validate and locate sex-related genes, and levels of E 2 and T were quantified to understand sex steroid synthesis., Results: Sexual dimorphism in growth became evident starting from 90 dpf. Histological observations revealed that morphological sex differentiation in females and males occurred between 20 and 25 dpf or earlier and 30-35 dpf or earlier, respectively, corresponding to the appearance of the ovarian cavity or efferent duct anlage. Transcriptome analyses revealed divergent gene expression patterns in testes and ovaries after 30 dpf. The periods of 40-60 dpf and 60-90 dpf marked the initiation of molecular sex differentiation in females and males, respectively. Male-biased genes (Sox11a, Dmrt1, Amh, Amhr2, Gsdf, Ar, Cyp17a2) likely play crucial roles in male sex differentiation and spermatogenesis, while female-biased genes (Foxl2, Cyp19a1a, Bmp15, Figla, Er) could be pivotal in ovarian differentiation and development. Numerous biological pathways linked to sex differentiation and gametogenesis were also identified. Additionally, E 2 and T exhibited sexual dimorphism during sex differentiation and gonadal development. Based on these results, it is hypothesized that in C. maculata, the potential male sex differentiation pathway, Sox11a-Dmrt1-Sox9b, activates downstream sex-related genes (Amh, Amhr2, Gsdf, Ar, Cyp17a2) for testicular development, while the antagonistic pathway, Foxl2/Cyp19a1a, activates downstream sex-related genes (Bmp15, Figla, Er) for ovarian development., Conclusions: This study provides a comprehensive overview of gonadal dynamic changes during sex differentiation and gametogenesis in C. maculata, establishing a scientific foundation for sex control in this species., (© 2024. The Author(s).)

Aniline (C 6 H 5 NH 2 ) is one of the hazardous aromatic amine where an amino group -NH 2 ) is connected to phenyl ring (C 6 H 5 ). Based on the evaluation of the 96-hour LC 50 of aniline, two sublethal concentrations (4.19 mg/l and 8.39 mg/l) were selected for acute exposure tests in freshwater fish Channa punctatus. The liver, gills and kidney of fish being the principal sites of xenobiotic material accumulation, respiration, biotransformation, and excretion are the focus of the present study. Throughout the exposure time, the comet assay revealed increased tail length and tail DNA percentage indicating maximum damage to liver, gills and kidney of treated group after 96 h. After acute exposure, there was a significant (p ≤ 0.05) increase in the enzymatic activity of glutathione-S-transferase (GST) and acetylcholinesterase (AChE), whereas decline in superoxide dismutase (SOD) and catalase (CAT) activity was observed. Meanwhile, levels of malondialdehyde (MDA) increased over the exposure period for both concentrations. After 96 h of exposure, degree of tissue change (DTC) was evaluated in liver, gill and kidney of aniline exposed fish. Additionally, light microscopy revealed multiple abnormalities in liver, gills and kidney of all the treated groups. Significant changes were observed in the levels of biochemical markers viz., glucose, triglyceride, cholesterol, aspartate transaminase, alanine transaminase and urea following a 96-hour exposure to aniline. Studies using ATR-FTIR and transmission electron microscopy (TEM) revealed changes in biomolecules and structural abnormalities in several tissues of the aniline-exposed groups in comparison to the control group respectively., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The widespread use of bisphenol A (BPA) has led to its ubiquity in the natural environment. It is extensively incorporated into different industrial products and is associated with deleterious health effects on both public and wildlife. The current trial was conducted to determine the toxic potential of bisphenol A using various parameters viz haematological, biochemical, and cytological in freshwater fish Channa punctatus. For this purpose, fish were exposed to 1.81 mg/l (1/4 of LC50) and 3.81 mg/l (1/2 of LC50) of BPA along with positive (acetone) and negative controls (water) for 96 h. The blood samples were collected at 24, 48, 72, and 96 h post-exposure. Compared to the control group, fish after acute exposure to BPA showed a significant decrease in HB content, number of red blood cells, PCV values whereas a significant increase in WBCs count was recorded with an increase in the exposure period. Besides, oxidative stress (determined as malondialdehyde content) increased as BPA concentration increased. Further, the activity of different antioxidant enzymes like catalase, and superoxide dismutase decreased significantly after treatment. Results also showed significantly increased frequency of morphological alterations, nuclear changes, and increased DNA damage potential of BPA in red blood cells. Further structural analysis of erythrocytes in maximally damaged group using Scanning Electron Microscopy was performed. The study concludes that BPA exhibits genotoxic activity and oxidative stress could be one of the mechanisms leading to genetic toxicity.

• vgc mRNA of murrel codes for 1272 amino acids (aa) and the predicted molecular weight of VgC protein is 141 kDa • The secondary structure of complete protein sequence of VgC showed the presence of α helix (47.48 %), β turns (3.3 %), random coils (35.85 %). • Protein interactions and phylogenetic analysis confirm its relationship with other non-phosphorylated Zona pellucida or Choriogenin proteins. • Expression of vgc gene at low levels of E 2 suggests that non-phosphorylated Vg protein (VgC), is synthesized earlier than phosphorylated Vgs (VgA and VgB) during oogenesis. Vitellogenin (Vg) is a female-specific egg-yolk precursor protein, synthesized in the liver of fish in response to estrogens. In the present study, complete gene of phosvitinless vitellogenin (vgc) was sequenced, its 3D structure was predicted and validated by web-based softwares. The complete nucleotide sequence of vgc was 4126 bp which encodes for 1272 amino acids and showed the presence of three conserved domains viz. LPD_N, DUF1943 and DUF1944. The retrieved amino acid sequence of VgC protein was subjected to in silico analysis for understanding the structural and functional properties of protein. mRNA levels of multiple vg genes have also been quantified during annual reproductive cycle employing qPCR. A correlation has been observed between seasonal changes in gonadosomatic index with estradiol levels and hepatic expression of three types of vg genes (vga, vgb, vgc) during ovarian cycle of murrel. During preparatory phase, when photoperiod and temperature are low; low titre of E 2 in blood induces expression of vgc gene. A rapid increase in the levels of E 2 favours induction of vgb and vga genes in liver of murrel during early pre-spawning phase when photoperiod is long and temperature is high in nature. These results suggest that among three vitellogenin proteins, VgC is synthesized earlier than VgA and VgB during oogenesis. [ABSTRACT FROM AUTHOR]

The present study explores growth potential of two medicinal herbs, Withania somnifera (Ashwagandha or 'A') and Asparagus racemosus (Shatavari or 'S') after their dietary inclusion in fish, Channa punctatus (13.5 ± 2 g; 11.5 ± 1 cm). Three hundred well-acclimatized fish were distributed into 10 groups- C (Control), S1 (1% S), S2 (2% S), S3 (3% S), A1 (1% A), A2 (2% A), A3 (3% A), AS1 (1% A and S), AS2 (2% A and S), and AS3 (3% A and S), each having 10 specimens. Fish were fed with these diets for 60 days. The study was performed in triplicate. Growth indices- weight gain (WG), specific growth rate percentage (SGR%), feed intake (FI), and condition factor (CF), after 30 and 60 days, were found significantly (p < 0.05) up-regulated in all the groups, except S1, when compared to the C. A significant (p < 0.05) increase in final body weight (FBW) was noticed in all the groups, except S1, after 60 days. Relative to the control group, activities of lipase and amylase in the gut tissue were elevated in all groups, at both sampling times, with the exception of lipase in S1 at 60 days, and amylase in S1 at day 30 and day 60 and S2 at day 60. The mRNA expression of myogenic regulatory factors (MRFs) was also found to be significantly (p < 0.05) up-regulated with the highest fold changes recorded in AS3 for myoD (3.93 ± 0.91); myoG (6.71 ± 0.30); myf5 (4.40 ± 0.33); MRF4 (4.94 ± 0.21) in comparison to the C. [Display omitted] • Diets with W. somnifera and A. racemosus significantly improve growth indices. • The combinatory diet – AS3 significantly increases digestive enzyme activities. • AS3 significantly (p < 0.05) enhances the myogenic regulatory factor (MRF) genes. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA), used in polycarbonate plastics and epoxy resins is a ubiquitous substance. This study aimed to assess the changes in the lipid profile of Channa punctatus after 30 days exposure to BPA. Fish were divided into five groups. Out of these, three groups were exposed to different sublethal concentrations of BPA. Two groups served as control groups, one without BPA or solvent and the other with the solvent but without BPA. After 30 days, blood was collected and serum lipid profile was determined. There was a significant increase in total lipids, triglycerides, total cholesterol, very low density lipoprotein (VLDL) and low density lipoprotein (LDL) at all test concentrations. At the two highest test concentrations serum high density lipoprotein (HDL) showed a significant decrease. These results suggest that long term BPA exposure induces hyperlipidemia in fish, interferes with lipid homeostasis, thereby, impairing normal physiological processes and the health of fish. The study also highlights the possibility of using changes in lipid profile as a marker of BPA induced stress. [ABSTRACT FROM AUTHOR]

The kidney and liver, tissues of Channa punctate were all destroyed after administration to sub-lethal quantities of parathion according to all histological findings. Histopathological changes in the kidney, liver, such as those seen in this research and prior research, can cause serious physiological difficulties in fish, eventually resulting in death. To summaries, the results of the current histological research show a direct link between pesticides exposure with histopathological problems across several tissues. [ABSTRACT FROM AUTHOR]

Monocrotophos (MCP) insecticides are used worldwide for protecting crops against pests. It has been reported as a pollutant that possesses long-term effects on the freshwater ecosystem. In the ecosystem, fishes are more vulnerable to aquatic pollutants as they are in direct contact with the environment. The present study was carried out to evaluate the toxic effect of MCP in freshwater fish species Channa punctatus (Bloch) under in-vitro conditions. Fish were exposed to acute dose (96 hrs LC50 = 53.996 mg/L) for 96 h of MCP. Increased SOD activity was observed at 24 hrs; however, it was significantly high in gills and kidneys at 96 hrs and in the liver at 72 hrs compared to the control. Histopathological alterations were also observed viz. fused and swollen tips of secondary lamellae, epithelial necrosis in the tissue of gills, vacuolization, congested sinusoids and disintegration of the hepatocytic cell membrane was observed in tissue of the liver and glomerular destruction, vacuolization of the inner epithelial cell was observed in the kidney at 96 hrs of MCP exposure. Overall, we observed at the median-lethal concentration (LC50) of MCP in Channa punctatus not only induce the SOD activity, but also alters the tissue histology in the vital organs of Channa punctatus. [ABSTRACT FROM AUTHOR]

For getting maximum yield intensive application of pesticides without proper disposal management has led to excess residues to flow into the neighboring aquatic ecosystems, inhabited by fish. So, the present study was conducted to assess the effects of organophosphate pesticide monocrotophos (MCP) in the level of markers in blood plasma and histopathology in air breathing fish Channa punctatus. Fishes were exposed to sublethal concentrations of the pesticide (2.7 and 5.4 mg L-1 of MCP) for a period of 30 days. Significant alterations in all the biochemical parameters were found to be dose dependent. Hyperglycemia was observed in plasma of fish after the exposure period. Increased activities of Aspartate Aminotransferase (AST), Alanine Aminotransferase (ALT), in blood plasma were found which indicated hepatic tissue damage. Total protein, albumin and albuminglobulin ratio decreased while a significant increase in creatine kinase was observed. The level of globulin increased at lower concentration of MCP while it decreased at higher concentration of MCP after 30 days. The blood serum levels of GGT (Gamma glutamyltransferase) were found decreased at all concentrations.Histopathological changes such as epithelial lifting, epithelial hyperplasia, epithelial necrosis, reduced inter lamellar space, desquamation and curling of secondary lamellae in gills; vacuolation, blood conjunctions and necrotic hepatocytes in the liver; and lamina propria, fusion of villi, and flattened villi in the kidney were observed. These structural alterations of the gills, liver, and kidney could affect respiration, osmotic and ionic regulation; absorption, storage and secretion and digestion, which in turn could adversely affect the growth and survival of freshwater fish, Channa punctatus. [ABSTRACT FROM AUTHOR]

Dietary lysine requirement of fingerling Channa punctatus (5.64 ±.08g) was determined by feeding isoproteic (450g/kg crude protein) and isoenergetic (14.73 kJ/g digestible energy) diets with graded concentrations of lysine (5, 10, 15, 20, 25, 30 and 35g/kg dry diet) to triplicate groups to apparent satiation at 08:00, 12:30 and 17:30 h for 12‐week. Absolute weight gain (AWG), specific growth rate (SGR), feed conversion ratio (FCR), protein gain (PG), lysine retention efficiency (LRE) and RNA/DNA ratio were found to increase with the increasing concentrations of lysine up to 20g/kg dry diet. Carcass protein increased up to 20g/kg dietary lysine, whereas carcass fat decreased significantly. Total serum protein and superoxide dismutase activity responded positively (p <.05), while aspartate aminotransferase and alanine aminotransferase activities negatively up to 20g/kg dietary lysine level. Quadratic regression analysis of AWG, FCR, PRE, LRE, Hb and Hct against dietary lysine levels indicated the lysine requirement ranging between 22.2 and 24.0g/kg dry diet corresponding to 49.4 and 53.4g/kg protein. [ABSTRACT FROM AUTHOR]

Developing a low-protein feed is important for the sustainable advancement of aquaculture. The aim of this study was to investigate the effects of essential amino acid (EAA) supplementation in a low-protein diet on the growth, intestinal health, and microbiota of the juvenile blotched snakehead, Channa maculata in an 8-week trial conducted in a recirculating aquaculture system. Three isoenergetic diets were formulated to include a control group (48.66 % crude protein (CP), HP), a low protein group (42.54 % CP, LP), and a low protein supplementation EAA group (44.44 % CP, LP-AA). The results showed that significantly lower weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER), and feed efficiency ratio (FER) were observed in fish that were fed LP than in the HP and LP-AA groups (P < 0.05). The HP and LP-AA groups exhibited a significant increase in intestinal villus length, villus width, and muscular thickness compared to the LP group (P < 0.05). Additionally, the HP and LP-AA groups demonstrated significantly higher levels of intestinal total antioxidant capacity (T-AOC), catalase (CAT), and superoxide dismutase (SOD) and lower levels of malondialdehyde (MDA) compared to the LP group (P < 0.05). The apoptosis rate of intestinal cells in the LP group was significantly higher than those in the LP and HP groups (P < 0.05). The mRNA expression levels of superoxide dismutase (sod), nuclear factor kappa B p65 subunit (nfκb-p65), heat shock protein 70 (hsp70), and inhibitor of NF-κBα (iκba) in the intestine were significantly higher in the LP group than those in the HP and LP-AA groups (P < 0.05). The 16s RNA analysis indicated that EAA supplementation significantly increased the growth of Desulfovibrio and altered the intestinal microflora. The relative abundances of Firmicutes and Cyanobacteria were positively correlated with antioxidant parameters (CAT and T-AOC), whereas Desulfobacterota was negatively correlated with sod and T-AOC. The genera Bacillus, Bacteroides, and Rothia were associated with the favorable maintenance of gut health. In conclusion, dietary supplementation with EAAs to achieve a balanced amino acid profile could potentially reduce the dietary protein levels from 48.66 % to 44.44 % without adversely affecting the growth and intestinal health of juvenile blotched snakeheads., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Mercury (Hg) is regarded as a serious hazard to aquatic life and is particularly prevalent in aquatic ecosystems. However, there is little evidence available regarding the toxicity of mercury chloride (HgCl 2 ) in vital organs of fish. This study was conducted to assess the effects of HgCl 2 (0.039 mg/L and 0.078 mg/L) on oxidative stress-mediated genotoxicity, poikilocytosis, apoptosis, and renal fibrosis after 15, 30, and 45 days of the exposure period. According to the findings, HgCl 2 intoxication in fish resulted in a significantly (P < 0.05) elevated lipid peroxidation (LPO), protein carbonyls (PC), lactate dehydrogenase (LDH) activity levels in kidney tissues and significantly (P < 0.05) increased reactive oxygen species (ROS), poikilocytosis, DNA tail length, and the frequency of apoptotic cells (AC%) in blood cells. Kidney's ultra-structure and histopathology revealed its fibrosis, which was evident by mRNA expression of targeted genes KIM1, NOX4, TGFβ, and NFϏβ. Different indicators of oxidative stress, apoptosis, and genotoxicity were altered in a dose and time-dependent manner, according to a two-way ANOVA analysis. There was a considerable positive link between oxidative stress and kidney fibrosis in the fish Channa punctatus, and it is evident from regression correlation and PCA data analysis. The kidney's ultra-structure evaluation and histopathology both revealed a noticeable fibrosis state. Additionally, a significant (P < 0.05) downregulation in PPARδ reveals that fish body was unable to combat diseases such as kidney fibrosis induced by HgCl 2 . This study shed fresh light on the mechanisms underlying nephrotoxicity caused by HgCl 2 exposure., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

[Display omitted] The widespread use of bisphenol A (BPA) has led to its ubiquity in the natural environment. It is extensively incorporated into different industrial products and is associated with deleterious health effects on both public and wildlife. The current trial was conducted to determine the toxic potential of bisphenol A using various parameters viz haematological, biochemical, and cytological in freshwater fish Channa punctatus. For this purpose, fish were exposed to 1.81 mg/l (1/4 of LC 50) and 3.81 mg/l (1/2 of LC 50) of BPA along with positive (acetone) and negative controls (water) for 96 h. The blood samples were collected at 24, 48, 72, and 96 h post-exposure. Compared to the control group, fish after acute exposure to BPA showed a significant decrease in HB content, number of red blood cells, PCV values whereas a significant increase in WBCs count was recorded with an increase in the exposure period. Besides, oxidative stress (determined as malondialdehyde content) increased as BPA concentration increased. Further, the activity of different antioxidant enzymes like catalase, and superoxide dismutase decreased significantly after treatment. Results also showed significantly increased frequency of morphological alterations, nuclear changes, and increased DNA damage potential of BPA in red blood cells. Further structural analysis of erythrocytes in maximally damaged group using Scanning Electron Microscopy was performed. The study concludes that BPA exhibits genotoxic activity and oxidative stress could be one of the mechanisms leading to genetic toxicity. [ABSTRACT FROM AUTHOR]

The Channa punctatus was exposed to various concentrations of chlorpyrifos 1.7, 1.8 and 1.9 ppm with contact time of 15, 30 and 45 days. After stipulated time, glycogen content in gill, liver, kidney, brain and muscle of treated fish found to be dropped after pesticide introduction. The efficiency of chlorpyrifos in the destruction of total glycogen content was evaluated by Langmuir and Freundlich isotherm models in relations of Qm and Kf. The spontaneity of the reaction in between chlorpyrifos and fish glycogen was determined by Gibb's free energy equation. The present analysis reports the metabolic dysfunction in response to pesticide toxicity in the fish. The glycogen level was estimated by method of Kemp and Kitsvan Heijhinger and the data obtained were analyzed by applying Langmuir and Freundlich isotherms and thermodynamic analyses. The result shows deteriorated levels of glycogen during all the exposure periods when compared with control. The results of the current study show the toxic nature of the chlorpyrifos on the glycogen content in gill, liver, kidney, brain and muscle of treated fish. [ABSTRACT FROM AUTHOR]

India is one of the fastest growing markets of Bisphenol A (BPA). BPA is used extensively in epoxy resins, polycarbonate plastics, thermal paper, electronic items etc. Recent studies have reported some of the world's highest concentrations of BPA in river waters from India. BPA is known to adversely affect fish physiology. In this study, Channa punctatus were exposed to three different sublethal concentrations of BPA for 15 days. Three other groups were co-exposed to the same concentrations of BPA and vitamin C. Haematological parameters were recorded from fish in all experimental groups. Exposure to BPA led to reduced RBC count, haemoglobin levels and haematocrit percentage while erythrocyte sedimentation rate and total leucocyte count increased. Studies of differential leucocyte count showed an increase in the percentage of neutrophils and a decrease in the percentage of lymphocytes while the percentages of other types of leucocytes remained unaffected. Co-exposure to vitamin C mitigated the effects of BPA exposure on haematological parameters. [ABSTRACT FROM AUTHOR]

Intestinal parasitic infections caused by helminths are globally distributed and are a major cause of morbidity worldwide. Parasites may modulate the virulence, gut microbiota diversity and host responses during infection. Despite numerous works, little is known about the complex interaction between parasites and the gut microbiota. In the present study, the complex interplay between parasites and the gut microbiota was investigated. A total of 12 bacterial strains across four major families, including Enterobacteriaceae, Morganellaceae, Flavobacteriaceae, and Pseudomonadaceae, were isolated from Channa punctata , infected with the nematode species Aporcella sp., Axonchium sp., Tylencholaimus mirabilis , and Dioctophyme renale . The findings revealed that nematode infection shaped the fish gut bacterial microbiota and significantly affected their virulence levels. Nematode-infected fish bacterial isolates are more likely to be pathogenic, with elevated hemolytic activity and biofilm formation, causing high fish mortality. In contrast, isolates recovered further from non-parasitised C. punctata were observed to be non-pathogenic and had negligible hemolytic activity and biofilm formation. Antibiogram analysis of the bacterial isolates revealed a disproportionately high percentage of bacteria that were either marginally or multidrug resistant, suggesting that parasitic infection-induced stress modulates the gut microenvironment and enables colonization by antibiotic-resistant strains. This isolation-based study provides an avenue to unravel the influence of parasitic infection on gut bacterial characteristics, which is valuable for understanding the infection mechanism and designing further studies aimed at optimizing treatment strategies. In addition, the cultured isolates can supplement future gut microbiome studies by providing wet lab specimens to compare (meta)genomic information discovered within the gut microenvironment of fish., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Kumar, Roy, Parida, Bisai, Dhar, Jana and Das.)

Nucleotide-binding oligomerization domain-like receptors (NOD-like receptors or NLRs) are a family of intracellular pattern recognition receptors (PRRs) that initiates as well as regulate inflammatory responses. NLRs are characterized by a centrally located nucleotide binding domain and a leucine rich repeat domain at the C-terminal responsible for the recognition of intracellular microbe-associated molecular patterns (MAMPs) and danger-associated molecular patterns (DAMPs). In the present study in adult spotted snakehead we have investigated the sex-dependent tissue distribution of NLRs known to be associated with inflammation in teleost namely NOD1, NOD2, NLRC3, NLRC5, and NLRX1. Further, the sexual dimorphism in the expression of NLR transcript as well as the pro-inflammatory protein IL-1β was explored in fish under normal conditions, and in fish exposed to bacterial lipopolysaccharide (LPS). The NLRs show ubiquitous and constitutive expression in all the tissues. Moreover, a prominent disparity between males and females was observed in the basal expression of these genes in various tissues. The sexual dimorphism in NLR expression was also prominent when fish were exposed to LPS. Similarly, IL-1β exhibited sexual dimorphism in both normal as well as LPS-exposed fish., (© 2024. The Author(s).)

Paraquat dichloride is a broad-spectrum herbicide used worldwide. It is very fast acting and used to kill a wide range of grasses and broad-leaved weeds. Paraquat dichloride gets run off to aquatic water bodies, and its presence has been reported by various researchers, where its effect is certain on aquatic organisms. Fish are vulnerable to aquatic pollutants as they are in direct contact with their environment. Therefore, our study was designed to evaluate the effects of herbicide paraquat dichloride on histology of vital organs (gills, liver, and kidney) of the fresh water fish Channa punctatus (Bloch). Toxicity effects are evaluated under static renewal test conditions, and histological alterations were detected microscopically. Fish were exposed to acute dose (96hLC50/2 = 32.93 mg/L) for 96 h of paraquat dichloride. Simultaneous control was also maintained. Principal histopathological alterations in gills during acute exposure showed curling of secondary lamellae, aneurysm, gill bridging, and enlargement of the cartilaginous core. The tissue damages like melanomacrophage centers, pyknotic nucleus, large sinusoidal congestion, and cell fusion are some histological alterations observed in the liver after acute exposure. The changes in histoarchitecture observed in the kidney include an increase in Bowman's space, necrosis of glomeruli, and damage to collecting duct at acute exposure. The histopathological changes were more prominent with the duration of exposure in the experimental groups. The present study demonstrated that the vital organs exhibited significant damage, among all gill histology specifically got altered being directly exposed to paraquat dichloride. Paraquat dichloride exposure affects the histology of gills, liver, and kidney, thus impairing the vital functions like respiration, excretion, and metabolic regulation which in turn will affect the fish health and is a serious threat. Histopathological alteration in gills, liver, and kidney can be regarded as sensitive biomarkers of paraquat dichloride toxicological manifestations and thus can be utilized for ecotoxicological biomonitoring of aquatic bodies. [ABSTRACT FROM AUTHOR]