Fish Gills Research Articles

Transport stress induces innate immunity responses through TLR and NLR signaling pathways and increases mucus cell number in gills of hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂)

Transport stress poses a threat to most teleost fish in production, causing mass losses to the aquaculture industry. Fish gills are a mucosa-associated lymphoid tissue in direct contact with water, and they represent an ideal tissue type to study mechanisms of transport stress. In this study, hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂) were exposed to simulated transport stress for 16 h and then allowed to recover for 96 h. Gill tissues and blood samples were collected at 0 h, 2 h, 4 h, 8 h, and 16 h of transport stress and after 96 h of recovery, as well as from fish in a control group at the same sampling times. The activities of alkaline phosphatase, acid phosphatase, and superoxide dismutase and the total antioxidant capacity first increased and then decreased during the 16 h transport treatment. Exposure to 16 h of transport stress resulted in decreased serum triglyceride and total cholesterol contents, increased serum glucose content, increased activities of alanine aminotransferase and aspartate transaminase, and more mucus cells, compared with the control group. Transcriptome analysis revealed differential expression of 1525 genes (803 down-regulated and 722 up-regulated) between the control and 16 h transportation groups. Functional analyses revealed that the differentially expressed genes were enriched in immune response, signal transduction, and energy metabolism pathways. We found that tlr5, tnfɑ, hsp90ɑ, il-1ß, map2k4, il12ba were clearly up-regulated and arrdc2, syngr1a were clearly down-regulated following 8 h and/or 16 h simulated transport after qRT-PCR validation. These findings suggested that Toll- and NOD-like receptor signaling pathways potentially mediate transport stress. Transport stress altered innate immunity responses and energy use in the gill tissues of hybrid yellow catfish. After 96 h of recovery, only alanine aminotransferase and alkaline phosphatase activities and the number of mucus cells had returned to control levels. We speculate that for juvenile yellow catfish to recover to a normal state, a recovery period of more than 96 h is required after 16 h of transportation. These results provide new perspectives on the immune response of yellow catfish under transport stress and theoretical support for future optimization of their transportation.

BIOACCUMULATION FACTOR (BAF) IN FISH CAUGHT IN A RIVER IMPACTED BY EFFLUENTS FROM AN ALUMINA PLANT IN THE EASTERN BRAZILIAN AMAZON

The rivers of the Amazon are important water resources for the planet however they are gradually suffering from anthropic impacts, especially those arising from mining and industrial activity. In this study, the bioaccumulation factor of toxic elements in tissues of fish species collected in the Murucupi River, a local impacted by effluents from an alumina factory located in Barcarena, in the Brazilian Amazon, was evaluated. Twenty samples were collected from three species of fish Cichla spp, Eigenmannia sp., and Angelfish. The element Al, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were analyzed in fish tissue and gills using inductively coupled plasma optical emission spectrometry. Regarding the concentration of the elements evaluated in the tissue, only Pb was not in compliance with the legislation. The BAF for the fish tissue samples indicated Cu bioaccumulation for the species Cichla spp (1130 L.kg-1) around seven times higher than the established limit, Eigenmannia sp. (2885 L.kg-1) fourteen times larger, and Angelfish (1640 L.kg-1) eight times larger. Ni also showed bioaccumulation for the specie Cichla spp (150 L.kg-1) and Eigenmannia sp. (145 L.kg-1) around one and a half times higher than recommended for both species. Zn showed bioaccumulation for the species Cichla spp (4212 L.kg-1), Eigenmannia sp. (3538 L.kg-1) around four times higher for both species, and Angelfish (7942 L.kg-1) around eight times higher. These elements with BAF above the recommended can present risks to the biota and consumers.

Comparative toxicity of silver nanoparticles and silver nitrate in freshwater fish Oreochromis mossambicus: A multi-biomarker approach

Silver nanoparticles (AgNPs) in the aquatic environment affect ecological repercussions and have fatal impacts on aquatic animals. The current study examined and correlated the toxicity of silver nitrate (AgNO3) and silver nanoparticles (AgNPs) to the Mozambique tilapia, Oreochromis mossambicus. The comparative toxicity studies were done by exposing O. mossambicus to various doses of AgNO3 and AgNPs (0, 25, 50, 75, and 100 μg/L) over a 7-day subacute exposure period. AAS analysis was used to detect Ag accumulation, while the histological examination established gill tissue damage. Oxidative stress affects lipid peroxidation (LPO) and protein carbonyl activity (PCA) in the gill tissue. Antioxidant parameters such as glutathione-S-transferase (GST), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase activity (CAT), and non-enzymatic antioxidants such as metallothionein (MT) and reduced glutathione. The serum in the blood was used to determine non-specific immunological characteristics such as lysozyme (LYZ), myeloperoxidase (MPO), and respiratory burst activity (RBA). The neurotoxic impact of acetylcholine esterase activity (AChE) was investigated in brain tissues. The findings demonstrated that larger concentrations of AgNO3 than AgNPs improved enzymatic antioxidant activities in the gill tissue. Histological examination of fish gills demonstrated that both AgNPs and AgNO3 induced telangiectasia and epithelial cell hyperplasia. By increasing the concentration of AgNPs and AgNO3, the present research demonstrated that silver accumulation leads to inefficient oxidative stress and altered enzymatic and non-enzymatic parameters, leading to cellular damage.

Fish funnel their food with jets

Unlike humans, many fish grab their food by sucking up the water that surrounds it. Once sucked into the fish's mouth, the food then gets swallowed up. What of the water that carried it there? The simplest way for water to exit is across the gills, but if food just followed suit, then fish would be inhaling and spewing it out through their gill slits. Pauline Provini, from Département Adaptations du Vivant, Paris, France, wasn't convinced that this would be the most elegant option and wondered whether fish independently filter their food away from the water. Together with Alexandre Brunet, Andrea Filippo and Sam Van Wassenbergh, they set out to see what goes on inside a fish's mouth while eating.As if it's not challenging enough to see into a fish's mouth, Provini and colleagues needed to see how food and water swirl around inside; it's hard to persuade a fish to say ‘ah’ and take a peek. As the next best thing, the team used fluoroscopy – moving x-rays – to see what happens inside the mouths of two kinds of fish, carp and tilapia, from multiple angles. It's hard to see how the food and water swirl about using fluoroscopy alone, so they used metal markers, which show up really well on x-ray images. First, they implanted fish food pellets with small metal beads. Next, to see the flow of water, they crafted an armada of miniscule floats, by encasing 0.4 mm long metal rods in tiny foam life jackets. These drifted about in the water, waiting to be taken in by the hungry fish when they sucked up their food.The researchers found that the fish used their expandable mouths to create a spout of water, a fast-flowing fluid funnel that shifts water down the centre of the mouth, from the front to the back. Provini and colleagues had wondered before whether this was the case, but they had now seen it first-hand. Pieces of food hitch a ride on this water jet and, instead of being belched out of the fish's gill slits, are taken to the entrance of the oesophagus, the muscular tube that leads to the stomach.But the story doesn't end there. The fish then synchronised the movements of their jaws and throat to waft the food back and forth a little in their mouth – a form of rhythmical gargling. Provini and colleagues suggest that the fish's ability to extend the consideration they gave to their food was a way to sample and sift the tastiest morsels, before rejecting unpalatable scraps.In addition, Provini saw that the tiny floats then swirled around the edges of the fish’s mouths and out of their gill slits, without a single one ever getting swallowed. Astonishingly, the fish managed to avoid swallowing any water by mistake. Far from being messy eaters, it seems that these fish have impeccable and quite particular table manners.

Anthelmintic efficacy of Copaifera reticulata oleoresin in the control of monogeneans and haematological and histopathological effects on Colossoma macropomum

This study investigated for the first time the anthelmintic efficacy of therapeutic baths with Copaifera reticulata oleoresin and nanoemulsion with this oleoresin against monogeneans of Colossoma macropomum, as well as the haematological and histological effects in this fish. In the therapeutic baths of three consecutives were used 100 mg/L of C. reticulata oleoresin or 250 mg/L of nanoemulsion containing C. reticulata oleoresin. Therapeutic baths with 100 mg/L of C. reticulata oleoresin had anthelmintic an efficacy of 48.5% against monogeneans (Anacanthorus spathulatus, Notozothecium janauachensis and Mymarothecium boegeri), while baths with nanoemulsion of C. reticulata oleoresin had not anthelmintic efficacy, which was discussed. Baths for 1 h with 100 mg/L of C. reticulata oleoresin or 2 h with 250 mg/L of C. reticulata nanoemulsion increased levels of plasma total protein and glucose, mean corpuscular volume (MCV) and neutrophils number in C. macropomum and decreased in the number of total leucocytes and lymphocytes. In the gills of fish exposed and controls occurred detachment of the epithelium, hyperplasia and hypertrophy, resulting in moderate fusion of the secondary lamellae. Therefore, therapeutic baths with C. reticulata oleoresin and nanoemulsion of C. reticulata oleoresin have a low toxicity to C. macropomum, as there were few changes to the blood parameters.

Isolation, Identification and Characteristics of Aeromonas caviae from Diseased Largemouth Bass (Micropterus salmoides)

The largemouth bass (Micropterus salmoides) is one of the most economically valuable fish species in China. In this study, a bacterial pathogen was isolated from the internal organs of diseased M. salmoides, and the strain was named WH21406. This isolate was identified as Aeromonas caviae on the basis of its morphology, biochemical features and 16S rDNA phylogenetic analysis. Four virulence genes related to pathogenicity, namely, flagella (fla), elastase (ela), haemolysin (hly) and aerolysin (aer), were detected in this isolate. The median lethal dosage (LD50) of A. caviae WH21406 for M. salmoides was calculated to be 3.46 × 105 CFU mL−1. The histopathological analysis showed obvious tissue damage in the gill, liver, kidney, spleen and gut of the diseased fish. The antibiotic susceptibility test demonstrated that strain WH21406 was highly sensitive to enrofloxacin, norfloxacin, streptomycin and amikacin. The results of this study provide a foundation for the diagnosis, prevention and treatment of A. caviae infection in M. salmoides.

The antioxidant defense capacities and histological alterations in the livers and gills of two fish species, Oreochromis niloticus and Clarias gariepinus, as indicative signs of the Batts drain pollution

The impacts of the Batts drain on two chronically exposed fish (O. niloticus and C. gariepinus) were assessed using multiple biomarkers. Concentrations of metals in water and sediments (Cu, Zn, Fe, Cd, Pb, and Al) showed significant elevations near the Batts discharges (site 2) compared to the reference site (site 1). The liver and gills of fish collected from site 2 showed marked elevations in the catalase, superoxide dismutase, glutathione peroxidase, and thiobarbituric acid reactive substance levels. In addition, significant reductions in glutathione-reduced contents were also recorded. Tissue and species-specific antioxidant responses were associated with excessive generations of reactive oxygen species, which were visualized fluorescently. Various histological alterations were observed in the gills and livers of both species. These alterations varied between compensatory responses (ex: epithelial thickening and lifting) and irreversible damage (ex: necrotic degeneration). Based on the level of lipid peroxidation and the frequency of histopathological modifications, O. niloticus demonstrated greater resistance to the same level of pollution than C. gariepinus. Using integrated biomarkers to evaluate the real impacts of untreated discharges of the Batts drain is applied for the first time on the selected fish species at the studied sites.

Eradication of Livoneca redmanii infestation in cultured Argyrosomus regius

Two Argyrosomus regius nursery ponds suffered from high mortality during the summer season of 2020. Diseased fish showed signs of respiratory distress, mainly during hot days. Physiochemical pond water parameters were normal, except dissolved oxygen was lower than the optimum level. Livoneca redmanii (Cymotidae, Isopoda) was isolated from the gill chamber of infested fish. The infestation percent was 41 and 33%, and the intensity was 1.146 and 1.06 in the first and second ponds, respectively. The diseased fingerlings were infested in the natural habitat (Mediterranean Sea) before collection for culture. L. redmanii infestation was associated with high economic losses due to direct fish mortality, reduced growth rates and lower condition factor. The molecular study confirmed the presence of L. redmanii based on the phylogenetic analysis of 16S rRNA and COI gene sequences. Infested fish gills showed massive destruction in gill filaments, sloughing and curling of secondary gill lamellae with the detachment of the cartilaginous core supporting the primary gill filaments. Deltamethrin and trichlorfon effectively eradicated L. redmanii at concentrations of 12.5 μg.l−1 and 0.5 mg.l−1, respectively. The lowest detectable deltamethrin residue in treated pond water was 2.18 μg.l−1 at 120 h, with a half-life of 47.63 h.

Transcriptomic profiles of Florida pompano (Trachinotus carolinus) gill following infection by the ectoparasite Amyloodiniumocellatum

The dinoflagellate Amyloodinium ocellatum is an important pathogenic parasite infecting cultured marine and brackish water fishes worldwide. This includes cultured Florida pompano (Trachinotus carolinus), which is one of the most desirable marine food fish with high economic value in the USA. A. ocellatum infects fish gills and causes tissue damage, increased respiratory rate, reduced appetite, and mortality, especially in closed aquaculture systems. This study mimicked the natural infection of A. ocellatum in cultured pompano and conducted a transcriptomic comparison of gene expression in the gills of control and A. ocellatum infected fish to explore the molecular mechanisms of infection. RNA-seq data revealed 604 differentially expressed genes in the infected fish gills. The immunoglobulin genes (including IgM/T) augmentation and IL1 inflammation suppression were detected after infection. Genes involved in reactive oxygen species mediating parasite killing were also highly induced. However, excessive oxidants have been linked to oxidative tissue damage and apoptosis. Correspondingly, widespread down-regulation of collagen genes and growth factor deprivation indicated impaired tissue repair, and meanwhile the key executor of apoptosis, caspase-3 was highly expressed (25.02-fold) in infected fish. The infection also influenced the respiratory gas sensing and transport genes and established hypoxic conditions in the gill tissue. Additionally, food intake and lipid metabolism were also affected. Our work provides the transcriptome sequencing of Florida pompano and provides key insights into the acute pathogenesis of A. ocellatum. This information can be utilized for designing optimal disease surveillance strategies, future selection for host resistance, and development of novel therapeutic measures.

Effect of lavander (Lavandula angustifolia) and laurel (Laurus nobilis) essential oils as anesthesics in rainbow trout (Oncorhynchus mykiss)

In this study, anesthetic effects of lavender ( Lavandula angustofolia ) and laurel ( Laurus nobilis ) essential oils were investigated in rainbow trout ( Oncorhynchus mykiss ). Fish (avarege 10 g) were exposed to different concentrations of essential oils (5, 10, 20, 50, 70, 100, 150, 200, 300, 400, 500 and 600 mg L −1 ). Anesthesia induction and recovery times were evaluated. In addition, histopathological effects of the essential oils in fish tissues were determined after deep anesthesia. As a result of this study, lavender essantial oil at 200 mg L −1 dose and laurel essential oil at 400 mg L −1 dose showed ideal anesthetic effects on rainbow trout. At these concentrations, deep anesthesia (Stage 4) induction times were 258.0 s for lavender and 189.5 s for laurel. Recovery times at these concentrations were 41 s for lavender and 129.5 s for laurel. No histopathological finding in gill, liver and kidney was observed. Consequently, this study was demostrated that lavender and laurel essential oils can be used as effective anesthetic in rainbow trout. • Anesthetic effects of laurel essential oil on rainbow trout determined for the first time in this study. • Laurel essential oil at 400 mg L −1 dose and lavender oil at 200 mg L −1 dose are suitable for anesthesia in rainbow trout. • No histopathological findings were found in gill, liver and kidney of fish exposed to 600 mg L −1 EOs. • This study was demostrated that lavender and laurel essential oils can be used as effective anesthetic in rainbow trout.

ISOLATION AND IDENTIFICATION OF POTENTIAL PATHOGENIC BACTERIA IN CARP (Cyprinus carpio LINNAEUS, 1758) CULTURED IN FISH FARMS, KASHMIR

The purpose of this research was to find out if there were any possibly disease-causing bacteria in carp cultured in Central and South Kashmir, as well as to find what species they were. Fish samples were taken from different local fish farms of the Srinagar and Anantnag districts. Once a week, three fish samples were collected from each farm and repeated three times. Bacteria were found in the fish's mucous membranes, gills, liver, and kidneys, among other places. To determine the bacteria's species, the results of each target organ's isolation were biochemically evaluated. Potential pathogenic bacteria found in carp from this research are (21.02%) Aeromonas sp., (7.64 %), Staphylococcus sp., (3.28%) Shigella sp., (14.65%) Bacillus sp., (3.82%) Proteus sp., (1.91%) Salmonella sp., (9.55%) E. coli, (6.37%) Enterobacter sp., (8.92%) Klebsiella sp., (10.83%) Pseudomonas sp., (5.73%) Acinetobacter sp., (3.82%), Flavobacterium sp. and ,(1.91% ) Serratia sp. Based on the results of research that has been done, we observed that bacterial infections are the most prominent microbiological agents impacting cultured fish, Aeromonas sp. and Bacillus sp. were most prevalent in fish microbiota. Contamination of fish's natural environment may have an impact not only on the health of fish stocks but also on public health, as fish and fish products can be a source of human pathogens. This study offers some inputs on likely bacterial infestation of fish and fish products which can compromise public health.

Comprehensive transcriptomic analysis reveals insights into the gill response to hypoxia and Poly I:C in Qihe crucian carp Carassius auratus

Hypoxia occurrence is potentiated by eutrophication caused by human activities and it may be the most dramatically increasing environmental factor as a result of the climate change-led increasing temperatures. The crucian carp Carassius auratus is an important aquaculture economical freshwater species and is also a potential model for the study of physiological adaptation. However, the transcriptomics and genomics data available for this species are still scarce. The gills of fish are the major organ of hypoxia and other stresses. In this study, we studied the effect of the exposure to hypoxia (1.0 mg O2/L for 7 d) and 2 mg/mL Poly I:C on the gene expression of the gills of Carassius auratus using the Illumina sequencing platform. Comparison of the gene expression levels between the experimental and control groups showed differentially expressed genes (DEGs). The DEGs were mainly annotated into glycolysis, oxidative phosphorylation and immune system categories based on the KEGG database. In glycolysis pathway, lactate dehydrogenase, malate dehydrogenase, glyceraldehyde 3-phosphate dehydrogenase, enolase and succinate dehydrogenase were identified. In addition, the DEGs were enriched in the immune-related pathway functions, including pattern recognition receptor (PRR), antigen processing and presentation, B cell and T cell receptor signaling pathways, natural killer (NK) cell mediated cytotoxicity, Fc gamma R-mediated phagocytosis, and the JAK-STAT, p53 and cytokines signaling pathways. This study also produced potential hypoxia biomarkers including FOS, JUN B, lysosomal acid lipase, and HIF-1α. HIF-1 signaling pathway was significantly down-regulated after hypoxia and Poly I: C exposure. Hence, the data generated here may offer a valuable resource information for the further study of the immune response and also provide improved strategies against hypoxia and Poly I:C in teleost fish.

Thermo-hydraulic performance improvement with nanofluids of a fish-gill-inspired plate heat exchanger

The plate heat exchanger (PHE) is an important component for parameters such as size, weight, high temperature and high pressure in many nanotechnological applications. Improving the thermo-hydraulic performance of PHEs along with technological developments are among the major challenges. The performance of PHEs can be improved by design, fabrication according to design, and the use of nanofluids. This causes economic problems. However, it can be compensated by improving the performance. In this study, inspired by fish gill shapes, fish gill grooves are designed on the plate surface of a PHE. This is a compact PHE that can be produced by additive manufacturing. It is compared to the performance of commercial Chevron angled PHE to verify the performance improvement under the same conditions. In addition, 0.5 vol% and 1 vol% concentrations of Cu and Al2O3 nanoparticle and water mixtures in hot and cold flow sides are used to increase the heat transfer according to the pressure drop of the fish-gill embossed PHE. The results of the study show that for water and 0.5 vol% Cu/water, its heat transfer rates are respectively 17.5% and 41% higher compared to the Chevron angled PHE. According to water usage in the fish-gill embossed PHE, the use of 0.5 vol% Cu/water nanofluid increases the heat transfer rate by 19.9% and the effectiveness by 24.5%. The narrow flow channels of the fins added to the plate surface cause an increase in the pressure drop of the fish-gill embossed PHE. As a result, nanofluid can be used to reduce the pressure drop compared to water usage.

Oxidative stress, apoptosis and serotonergic system changes in zebrafish (Danio rerio) gills after long-term exposure to microplastics and copper

Fish gills are in direct contact with the surrounding pollutants, and thus, potentially more vulnerable to microplastics (MPs) and heavy metals. The present study aimed to evaluate the long-term exposure effects of MPs and copper (Cu) in the gills of adult zebrafish (Danio rerio). To this end, zebrafish were exposed to MPs (2 mg/L), Cu (Cu25, 25 μg/L) and their mixture (Cu25 + MPs) for 30 days, and then oxidative stress, detoxification, antioxidant, metabolic and neurotoxicity enzymes/genes, as well serotonergic system and apoptosis genes, were evaluated in gills. In the mixture group, ROS levels were increased, while CAT and GPx activities were inhibited, indicating the induction of oxidative stress in zebrafish gills. This was followed by an increase of LPO levels and potential oxidative damage in zebrafish gills. The tryptophan hydroxylase 1a (tph1a) and caspase-3 (casp3) genes were significantly upregulated in Cu25 + MPs group, indicating a potential dysregulation of serotonin synthesis and apoptosis pathways, respectively. Overall, the present study contributes to improving the knowledge about the response of aquatic organisms to MPs and the potential ecological risk that these particles represent to the ecosystems.

Assessment of biochemical biomarkers of mosquitofish (Gambusia affinis (Baird et Girard, 1853)) on exposure to the insecticide cypermethrin

ABSTRACT Cypermethrin (CYP) is a synthetic pyrethroid insecticide, used in agriculture, and one of the most common contaminants in freshwater aquatic systems. This paper reports an evaluation of the toxicity of CYP in the mosquitofish, exposed to two concentrations (0.2 ng/L and 6.25 ng/L). The result revealed a significant modulation in the activity of antioxidants enzymes, superoxide dismutase, catalase and decreased acetylcholinesterase after 7 days. Hydrogen peroxide (H2O2) and malondialdehyde levels remained elevated throughout the exposure duration. CYP causes gills and liver oxidative stress, modifying the antioxidant enzymes. Principal component analysis highlighted relationship between biomarkers in functional response. These findings suggest that exposure to CYP can lead to various antioxidant processes in the fish gills and liver.

Bacterial Indicators of Contamination in Highly Impacted Segment of Tropical Lagoon, Southwest Nigeria

Increasing deterioration of coastal waters is a major public health concern in many regions of the developing world. This study investigates the impact of water quality on the proliferation of bacterial pathogens in surface water, sediment and tissues of fish, Sarotherodon melanotheron from the Makoko axis of Lagos Lagoon. Analysis of physicochemical characteristics and microbial quality of samples followed standard methods and procedures. Measured water quality parameters (water temperature, turbidity, pH, salinity and dissolved oxygen) which showed no significant variation (p>0.05) across study stations were within the Nigerian Federal Environmental Protection Agency set limit The highest total bacterial count (TBC) (214.09±43.95 x 105 CFU g-1), total coliform counts (TCC) (91.15±15.05 ×104 CFU g-1) and total faecal coliform (TFC) (36.22±12.98×10³ CFU g-1) were recorded in fish muscle tissue while the lowest TBC (52.39±39.72 x 105 CFU ml-1), TCC (33.45±33.94 ×104 CFU ml-1) and TFC (0.19±0.18×10³ CFU ml-1) were recorded in water sample. The bacterial species with the highest percentages of occurrence in water, sediment, fish gill and fish muscle tissue were Klebsiella pneumoniae (22.11 %), Enterobacter aerogenes (32.37 %), Escherichia coli (32.97 %) and E. coli (29.00 %) respectively. A very strong positive correlation (r = 1.00) was obtained between TBC in water and salinity as well as with dissolved oxygen levels. Likewise, the TBCs in fish parts (muscle tissue and gill) were positively correlated with the water temperature and turbidity. On the other hand, a negative correlation was obtained between pH and TBC in fish muscle tissue (r = -0.81) as well as with fish gut (r = -0.77). The relatively high counts of pathogenic bacteria species recorded during the study have serious public health implications.

Nutritional value and bioaccumulation of heavy metals in nine commercial fish species from Dachen Fishing Ground, East China Sea

The study evaluated the nutritional quality in muscle tissues of nine commercially important marine fish species. And the concentrations of trace metals (i.e. As, Hg, Cu, Pb, Cr, Cd and Zn) in the muscles (edible part) and tissues (gill and liver) of fishes caught from Dachen fishing ground, the coast of Zhejiang Province, East China Sea, were determined, and the values of target hazard quotient (THQ) and the carcinogenic risk (TR) were calculated for assessing human health risk. Significant differences(P < 0.05) were observed in the proximate chemical composition of fish muscles in these species. The muscle protein content of fish species ranged from 12.36 to 23.41%. The muscle lipid content of fishes ranged from 0.48 to 2.54%. The accumulation capacity of heavy metals (except Cr) in livers and gills was higher than that in muscles. In addition, the accumulation ability of most fishes is related to the water layer they live, the fishes living in the demersal layer showed more accumulation of heavy metals than the middle-upper layer(except Cu). Estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI) and the carcinogenic risk (TR) assessed for potential human health risk implications suggest that the values were within the acceptable threshold for human. However, the carcinogenic risk(TR) of As and Cr was close to the critical limit (10–4). Therefore, in order to ensure the health and safety of human consumption, the continuous monitoring of heavy metals in Dachen fishing ground area is suggested.

Identifikasi Endoparasit Pada Ikan Gabus ( Channa striata ) di Sungai Sebangau Palangka Raya Kalimantan Tengah

The study aimed at identifying of endoparasites that infect snakehead (Channa striata) fish as well as to determine the prevalence of the endoparasite species in snakehead fish then examined at Parasitology Laboratory of Fish Quarantine Station Quality Control and Safety of Fishery Products in Palangka Raya. Examination of endoparasites is done by observing the internal organs and by making a mucus smear which is examined under a microscope. From the results of the study found 2 types of parasites that infest snakehead fish in the Sebangau River, Palangka Raya, namely Procamallus sp dan Camallanus sp. The most common endoparasites that attack the gills of snakehead fish are Camallanus sp with a prevalence of 20% and an intensity of 3 cells/ind, and Procamallus sp with a prevalence of 10% and an intensity of 2 cell/ind.

New insights into the influence of myo-inositol on carbohydrate metabolism during osmoregulation in Nile tilapia (Oreochromis niloticus).

A two-factor (2 × 3) orthogonal test was conducted to investigate the effects of dietary myo-inositol (MI) on the osmoregulation and carbohydrate metabolism of euryhaline fish tilapia (Oreochromis niloticus) under sustained hypertonic stress (20 practical salinity units [psu]). 6 diets containing either normal carbohydrate (NC, 30%) or high carbohydrate (HC, 45%) levels, with 3 levels (0, 400 and 1,200 mg/kg diet) of MI, respectively, were fed to 540 fish under 20 psu for 8 weeks. Dietary MI supplementation significantly improved growth performance and crude protein content of whole fish, and decreased the content of crude lipid of whole fish (P < 0.05). Curled, disordered gill lamella and cracked gill filament cartilage were observed in the gill of fish fed diets without MI supplementation. The ion transport capacity in gill was significantly improved in the 1,200 mg/kg MI supplementation groups compared with the 0 mg/kg MI groups (P < 0.05). Moreover, the contents of Na+, K+, Cl− in serum were markedly reduced with the dietary MI supplementation (P < 0.05). The fish fed 1,200 mg/kg MI supplementation had the highest MI content in the gills and the lowest MI content in the serum (P < 0.05). Additionally, the fish fed with 1,200 mg/kg MI supplementation had the highest MI synthesis capacity in gills and brain (P < 0.05). Dietary MI markedly promoted the ability of carbohydrate metabolism in liver (P < 0.05). Moreover, fish in the 1,200 mg/kg MI groups had the highest antioxidant capacity (P < 0.05). This study indicated that high dietary carbohydrate would intensify stress, and impair the ability of osmoregulation in tilapia under a long-term hypersaline exposure. The supplementation of MI at 1,200 mg/kg in the high carbohydrate diet could promote carbohydrate utilization and improve the osmoregulation capacity of tilapia under long-term hypertonic stress.

Amphora coffeaeformis diatom involved in reducing the susceptibility of Nile tilapia ( Oreochromis niloticus ) fingerlings to Aeromonas hydrophila infection by boosting immune and antioxidant responses and improving growth performance indicators

In the present study, the Amphora coffeaeformis diatom was applied in different concentrations to the diet of Nile tilapia (Oreochromis niloticus) to investigate its potential effects in improving growth performance, as well as enhancing immune and antioxidant responses to control Aeromonas hydrophila infection. The tilapia fingerlings were divided into 4 groups, and for 4 weeks were fed A. coffeaeformis at various concentrations (0, 1, 2 and 3%). Growth-stimulating activity from dietary A. coffeaeformis was observed, particularly in the 2% and 3% treatment groups. Furthermore, serum immunoglobulin M (IgM), nitric oxide (NO), malondialdehyde (MDA), total-superoxide dismutase (T-SOD), catalase (CAT), and glutathione peroxidase (GPx) were evaluated at the 2nd and 4th weeks from the onset of feeding and showed significant improvement (p < 0.05) in the 2 and 3% groups. At the end of the feeding trial, the tilapia were challenged via an intraperitoneal (IP) injection of virulent Aeromonas hydrophila. Fish survival, serum IgM, nitric oxide, MDA, T-SOD, CAT, GPx, and liver, kidney, spleen, and gill histopathology were all evaluated post challenge. Significant improvements in both immunological and antioxidant parameters continued until the post-challenge measurements. Overall survival was significantly increased in the 2 and 3% groups, compared to the control and 1% groups. Histopathological examination revealed a decrease in the degenerative and destructive effects of A. hydrophila infection on the liver, kidneys, spleen, and gill tissues, indicating that dietary A. coffeaeformis administered at concentrations of 2 and 3% could be recommended as a feed additive for the control of A. hydrophila infection in Nile tilapia.