Electro-Immobilisation and Fish Welfare: An Investigation into Stress, Consciousness, and Physiological Aspects During Slaughter.

The aquaculture industry frequently employs various slaughter methods that subject fish to inhumane conditions, resulting in significant suffering. This study examined the effects of electrical method on the welfare of farmed fish (Mesopotamichthys sharpeyi) compared to air asphyxiation. Fish captured with electricity exhibited calm behavior until death, in contrast to fish treated with air asphyxiation, which exhibited violent responses within 4 minutes of capture. The electrical method achieved a complete state of unconsciousness 7 minutes faster than air asphyxiation. Our results show that air asphyxiation raised cortisol levels more than the electrical method, with no significant difference in glucose and lactate concentrations. Electrically treated fish had higher superoxide dismutase and liver-reduced glutathione levels, while suffocated fish showed elevated GSH and liver catalase levels. Radiographs revealed no fractures or skeletal changes. Electrical stunning had no effect on gill tissue, but caused brain tissue hemorrhage, whereas air asphyxiation caused less damage. Air asphyxiation caused gill tissue issues but less brain damage. Consciousness loss is crucial for humane practices. Specific electrical currents (110V for 30s) could improve aquaculture and fish welfare.

Exploring the combined interplays: Effects of cypermethrin and microplastic exposure on the survival and antioxidant physiology of Astacus leptodactylus.

Plastic waste and micro/nanoplastic particles pose a significant global environmental challenge, along with concerns surrounding certain pesticides' impact on aquatic organisms. This study investigated the effects of microplastic particles (MPPs) and cypermethrin (CYP) on crayfish, focusing on biochemical indices, lipid peroxidation, oxidative stress, hematological changes, and histopathological damage. After determining the LC50-96 h value (4.162 µg/L), crayfish were exposed to sub-lethal concentrations of CYP (1.00 ppb (20%) and 2.00 ppb (50%)) and fed a diet containing 100 mg/kg MPPs for 60 days. Hemolymph transfusion and histopathological examinations of the hepatopancreas were conducted. The results showed significant alterations in crayfish. Total protein levels decreased, indicating protein breakdown to counteract contaminants, while total cholesterol and triglyceride levels declined, suggesting impaired metabolism. Glucose levels increased in response to chemical stress. The decline in total antioxidant capacity highlighted the impact of prolonged xenobiotic exposure and oxidative stress, while increased CAT, SOD, and MDA activities helped mitigate oxidative stress and maintain cellular homeostasis. The elevated total hemocyte count, particularly in semi-granular cells, suggests their active involvement in the detoxification process. Further research is needed to fully understand the implications of these effects.

Beyond the surface: Consequences of methyl tert-butyl ether (MTBE) exposure on oxidative stress, haematology, genotoxicity, and histopathology in rainbow trout.

Concerns have been raised about the possible environmental effects of methyl tert-butyl ether (MTBE), which is widely used as a gasoline additive. This research aimed to look at the consequences of MTBE contamination on rainbow trout (Oncorhynchus mykiss), emphasizing oxidative stress, genotoxicity, and histopathological damage. After determining the LC50-96 h value, the effects of sub-lethal doses of MTBE (0 (control), 90, 180, and 450 ppm) on rainbow trout were investigated. In fish tissues, the levels of oxidative stress indicators such as malondialdehyde (MDA) and superoxide dismutase (SOD) were measured. The comet assay, which measures DNA damage in erythrocytes, was used to determine genotoxicity. Histopathological examinations were done on liver and gill tissues to examine potential structural anomalies. The results of this study show that MTBE exposure caused considerable alterations in rainbow trout. Increased oxidative stress was demonstrated by elevated MDA levels and decreased SOD activity, while the comet assay revealed dose-dependent DNA damage, implying genotoxic effects. Histopathological study revealed liver and gill tissue abnormalities, including cell degeneration, necrosis, and inflammation. Overall, this research highlights the possible sub-lethal effects of MTBE contamination on rainbow trout, stressing the need of resolving this issue. Future research should look at the impacts of chronic MTBE exposure and the possibility of bioaccumulation in fish populations.

Anodonta cygnea, a freshwater swan mussel, exposed to diazinon: toxicity thresholds in behaviour and physiology.

Swan mussels (Anodonta cygnea) have been suggested as suitable bioindicators for the presence of pollutants in the environment. Application of the physiological and behavioral markers in these sessile species can be beneficial for environmental monitoring. The present study aimed to investigate the relationship between the behavioral disorders of movement and siphoning associated with the inhibition of tissue Acetylcholinesterase (AChE). For experiments, overally 120 bivalves of Anodonta cygnea (mean total length 80.33 ± 6.7 mm) were transported from the agricultural drains and canals in Sari county (Mazandaran Province, Iran) to our laboratory. First, the LC50-96 h of diazinon was estimated according to the Organization for Economic Co-operation and Development (OECD 1992) guideline with static water conditions. The sub-lethal toxicity pesticide experiments were conducted on the basis of the lowest observed effect concentration (LOEC) and the maximum acceptable toxicant concentration (MATC). The LC50-96 h, LOEC, and MATC values of diazinon were 85.2, 42.1, and 8.5 mg L- 1, respectively. Based on the observations of mussels' movement, the burrowing and displacement decreased with the concentration of toxicant in water. Moreover, the presence of diazinon in water and its exposure to experimental animals significantly reduces their siphoning rate. The RDA showed that the AChE activity had a higher correlation with the siphoning behavior than the movement behavior. The comparison of enzyme activity at different exposure and recovery times showed that there was a significant difference among the groups affected by the consumed pesticide (p = 0.001, between contrasts). The most remarkable morphometric characteristic was the siphon opening that was inversely correlated with the enzymatic activity. Studies in bioethics might benefit from paying attention to these traits that are directly related to the level of toxicity and behavioral adaptations required for animal survival.

Cutaneous mucosal immune-parameters and intestinal immune-relevant genes expression in streptococcal-infected rainbow trout (Oncorhynchus mykiss): A comparative study with the administration of florfenicol and olive leaf extract.

This study evaluated changes in cutaneous mucosal immunity (total protein (TP) and immunoglobulin (TIg), lysozyme, protease, esterase, and alkaline phosphatase (ALP)) and some immune-related genes expression (tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), interleukin-8, hepcidin-like antimicrobial peptides (HAMP), and immunoglobulin M (IgM)) in the intestine of rainbow trout (Oncorhynchus mykiss) orally-administrated florfenicol (FFC) and/or olive leaf extract (OLE), experimentally infected with Streptococcus iniae. The juvenile fish (55 ± 7.6 g) were divided into different groups according to the use of added OLE (80 g kg-1 food), the presence/absence of FFC (15 mg kg-1 body weight for 10 consecutive days), and the streptococcal infectivity (2.87 × 107 CFU mL-1 as 30% of LD50-96h). The extract's chemical composition was analyzed using the high-performance liquid chromatography (HPLC) system. The skin mucus and intestine of fish were sampled after a 10-day therapeutic period for all groups, and their noted indices were measured. Our results signified that the oleuropein, quercetin, and trans-ferulic acid were the most obvious active components of OLE which were found by HPLC analysis. The combined use of OLE and FFC could lowered some skin mucus immunological indices (e.g., TP, TIg, and ALP), and the gene expression of inflammatory cytokines (e.g., TNF-α and IL-1ß) of rainbow trout. Moreover, lysozyme and protease activities respectively were invigorated by the FFC and OLE treatment. Also, the use of OLE as a potential medicine induced the gene expression of HAMP. As the prevention approach, it would be recommended to find the best dose of OLE alone or in combination with the drug through therapeutics period before the farm involved in the streptococcal infection.

A bioassay on tissue cholinesterase activity of Rutilus kutum (Kamensky, 1901) exposed to some common pesticides in Iran.

The toxicological effects of three commonly used pesticides in Iran on the fries of Caspian kutum (Rutilus kutum, Kamensky, 1901) were investigated through determining 50.00% lethal concentration (LC50) 96hr and cholinesterase (ChE) inhibition. The LC50 96-hr of carbaryl, glyphosate, and malathion were equal to 11.69, 6.64, and 0.97 mg L-1, respectively, that were considered as harmful (10.00 - 100 mg L-1), toxic (1.00 - 10.00 mg L-1) and very toxic (< 1.00 mg L-1) compounds for this species. The exposure of fries to sub-lethal concentrations of the pesticides over 15 days indicated that the average of ChE activity in the head and trunk were 1086.89 ± 124.34 and 627.36 ± 99.60 mU min-1 per mg protein, respectively, with a significant difference relative to each other. There was a significant difference between fry exposed to all three pesticides and the control group in cholinesterase inhibition. The fries exposed to carbaryl (890.12 ± 28.08 mU min-1 per mg protein) and glyphosate (891.77 ± 31.61 mU min-1 per mg protein) showed lower ChE inhibition than those exposed to malathion (790.00 ± 58.14 mU min-1 per mg protein).

DNA damage, acetylcholinesterase activity, and hematological responses in rainbow trout exposed to the organophosphate malathion.

Effects of sub-lethal concentrations (0 (control), 0.009, 0.014, and 0.023 ppm) of the organophosphate insecticide "malathion" to rainbow trout (Oncorhynchus mykiss) after the determination of LC50-96 h value (0.093 ppm) were evaluated. Changes in biomarkers of neurotoxicity (acetylcholinesterase (AChE) activity), genotoxicity (DNA damage), and hematological parameters (red (RBC) and white (WBC) blood cell count, hemoglobin (Hb), hematocrit (Hct), mean cell hemoglobin (MCH), mean cell volume (MCV), and mean cell hemoglobin concentration (MCHC)) were assessed for a 15-day exposure. A significant time- and dose-dependent reduction in AChE activities of gill, muscle, brain, and liver tissues was found. However, the AChE activity was less affected by malathion concentration than by exposure time. DNA damage of erythrocytes at different malathion concentrations increased by increasing the experimental time up to the fourth day. A decrease in the count of WBC, RBC, and Hct and an increase in the number of MCH and MCV were observed by increasing malathion exposure dose and time (p < 0.05). An increase in the malathion concentration and exposure time significantly resulted in a decrease in Hb and an increase in MCHC. A significant improvement in AChE activity; DNA damage; and RBC, Hb, Hct, MCV, and MCH indices was detected during a 30-day recovery period, but the WBC count changed insignificantly. The recovery pattern based on 100% water exchange with clean water could be a successful strategy to improve the biomarker responses of rainbow trout habituating in contaminated aquatic environments.

Immunomodulatory effects of orally administrated florfenicol in rainbow trout (Oncorhynchus mykiss) following experimental challenge with streptococcosis/lactococcosis.

The purpose of the present work was to determine whether florfenicol (FFC) as the prominent broad-spectrum antibiotic could affect serum biochemical and immunological parameters, as well as immune-related genes expression in rainbow trout (55 ±â€¯7.6 g) challenged with the Lactococcus garvieae and Streptococcus iniae. In the first trial, the doses of the pathogens for challenge test were determined based on LD50. The therapeutic dosage of the drug (15 mg.kg-1 BW for 10 consecutive days) was administrated as medicated feed. After anesthesia, blood and kidney samples were collected from individual fish and were kept in deep freezing mode until the beginning of the measurements. Serum biochemical and enzymatic indices were measured using commercial kits. Immune parameters including total immunoglobulin level, lysozyme, ACH50, respiratory burst (RB), and phagocytic activities (PA) and the expression of immune genes namely TNF-α, IL-1ß, IL-8, and IgM was evaluated. The levels of lysozyme and RB activities, as well as the expression of TNF-α and IL-1ß genes, showed a significant increase in the FFC treated/infected fish compared to untreated diseased fish (P < 0.05). In contrast, serum total immunoglobulin and IgM-related genes expression were suppressed following drug administration represented by a significant reduction in untreated streptococcal infected fish compared to other treatments (P < 0.05). However, no significant effect of FFC was observed on serum ACH50 activity, PA values and IL-8-related gene expression (P > 0.05). These results demonstrated that FFC treatment could improve some physiological status including stress resistance and some liver function parameters, and much innate immunity was invigorated, but at the same time, the suppressive effects of FFC on acquainted immunity cannot be ignored.

Comparative single-dose pharmacokinetics of orally administered florfenicol in rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) at health and experimental infection with Streptococcus iniae or Lactococcus garvieae.

This study evaluates changes in the pharmacokinetic behavior of a single oral dose of florfenicol in rainbow trouts experimentally infected with Lactococcus garvieae or Streptococcus iniae. One hundred and fifty fish were randomly divided into three equal groups: 1-healthy fish, 2-fish inoculated with S. iniae (2.87 × 107 CFU/ml, i.p.), and 3-fish inoculated with L. garvieae (6.8 × 105 CFU/ml, i.p.). Florfenicol was administered to all groups at 15 mg/kg by oral gavage. Blood sampling was performed at 0, 2, 3, 6, 8, 12, 24, 48, 72, and 120 hr after drug administration to each group, and plasma concentration of florfenicol was assayed by HPLC method. The MICs of florfenicol were 1.2 µg/ml and 5 µg/ml against L. garviae and S. iniae, respectively. Healthy fish showed higher values for most of the PK/PD parameters as compared to fish infected with L. garvieae which was reversed in fish infected with S. iniae. Fish infected with L. garvieae showed decreased relative bioavailability accompanied by increased volume of distribution at steady-state (Vdss ) and total body clearance (ClB ). Infection with S. iniae increased the peak concentration of drug after administration (Cmax) and decreased elimination half-life (T1/2 ß ), central compartment volume (Vc ), and Vdss . In conclusion, infection with these bacteria can affect the pharmacokinetic behavior of florfenicol in rainbow trouts as shown by decreased bioavailability and increased total body clearance and volume of distribution in L. garvieae infection and decreased volume of distribution accompanied by increased Cmax in S. iniae-infected fish.

First isolation and identification of Aeromonas veronii and Chryseobacterium joostei from reared sturgeons in Fars province, Iran.

The purpose of the present study was to isolate and identify the pathogenic agents in Acipenser stellatus (Pallas, 1771) and Huso huso, (Linnaeus, 1758) reared in the south of Fars province, Iran which have shown infectious disease signs. Samples from spleen and kidney of 32 fishes showing septicemia symptoms such as decreasing of appetite, unbalanced swimming, expanded wounds, and petechia on the body surfaces, pectoral fins rot, visceral hemorrhage, bleeding on the spleen, and heart ascites were collected. Then samples were cultured on brain heart infusion agar growth media, stain and biological and biochemical tests on purified bacteria were performed. On the other hand, 16S rDNA region of the isolated organism was amplified using PCR. The amplified gene fragment was sequenced and evolutionary history was inferred by phylogenetic tree construction using neighbor-joining method. Results indicated that two bacterial species including Chryseobacteriumjoostei which isolated from the kidney of stellate sturgeon (43.00%), and Aeromonasveronii which isolated from the spleen of both sturgeon species (75.00% and 31.00% from beluga and stellate sturgeon, respectively), were recognized. Phylogenetic tree analysis showed that Fars isolated organisms including A. veronii and C. joostei had highest similarity with A. veronii bv veronii and C. joostei isolated from France, respectively.