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This study aimed to perform in vitro antiparasitic and antimicrobial tests with the essential oil (EO) of Schinus terebinthifolius against of fish and shrimp. The chemical composition of the EO of S. terebinthifolius was determined by gas chromatography. For the antiparasitic test, the protozoan Epistylis sp. obtained from parasitized Oreochromis niloticus was used, and exposed to different concentrations of EO (2%, 1%, 0.5%, 0.25%), and control with 1% grain alcohol. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) test with EO of S. terebinthifolius evaluated the antimicrobial potential, with serial dilutions starting at 2% and control with 1% grain alcohol, using the strains of Aeromonas hydrophila (2.2 × 108 CFU mL−1), Edwardsiella tarda, Vibrio parahaemolyticus, V. harveyi, and V. alginolyticus (2.0 × 108 CFU mL−1). Chemical analysis revealed that the major EO compounds of S. terebinthifolius were δ‐3‐Carene (56.00%) and α‐Pinene (16.89%). In the antiparasitic test, the concentration of 2% EO showed 100% efficacy against Epistylis sp. within 5 min. In the antimicrobial tests, the concentration of 2% EO was effective against all bacteria tested. The EO of S. terebinthifolius demonstrated antiparasitic and antimicrobial activity at a concentration of 2%, standing out as an alternative to conventional antibiotics. [ABSTRACT FROM AUTHOR]

This study investigated the in vitro antimicrobial and anthelmintic effect of copper nanoparticles (CuNPs) against the bacterium Aeromonas hydrophila, the monogeneans Dactylogyrus minutus, Dactylogyrus extensus, Gyrodactylus cyprini, and the cestode Schyzocotyle acheilognathi, as well as their toxicity to Cyprinus carpio Koi. In the antimicrobial in vitro test, the inhibition zone method and minimum inhibitory concentration (MIC) were performed. In order to determine the time and efficacy of monogenean parasite mortality, the parasites were exposed to CuNP concentrations of 20, 50, 100, 150, 200, and 300 mg L−1, and a control group with tank water and one with copper sulphate pentahydrate (CuSO4.5H2O) at a concentration of 0.3 mg L−1, performed in triplicate. The parasites were observed every 10 min for 300 min, and mortality was recorded. For the cestodes, parasites were immersed in CuNP concentrations of 50, 100, 150, and 300 mg L−1. At the end of the in vitro tests, the anthelmintic efficacy of each treatment was calculated. To assess the tolerance and toxicity in fish, they were exposed to CuNP concentrations of 0.6, 1.25, 2.5, 5, 10, 20, and 50 mg L−1 for 12 h. The MIC demonstrated that CuNPs effectively inhibited the growth of A. hydrophila up to a dilution of 12,500 mg L−1 and showed an inhibition zone of 14.0 ± 1.6 mm for CuNPs. The results of anthelmintic activity showed a dose‐dependent effect of concentration for both groups of parasites, with the most effective concentration being 300 mg L−1 in 120 min. In the toxicity test, the carps showed tolerance to lower concentrations. The study indicated that CuNPs were effective against the studied pathogens. However, it proved to be toxic to fish at high concentrations. The use of low concentrations is recommended still requires further investigation. [ABSTRACT FROM AUTHOR]

ABSTRACT The objective of this study was to evaluate the effect of dietary supplementation with Citrus sinensis (L.) Osbeck essential oil on the growth, immune system, and resistance to Aeromonas hydrophila infection in Colossoma macropomum fingerlings. The experiment was conducted with five treatments (control diet, Tween80 diet, and diets supplemented with 200, 400, and 800 mg L−1 of C. sinensis essential oil) with four replicates. At the end of the experimental period, growth parameters were measured, and blood samples were collected for thrombogram, leukogram, and phagocytic activity analysis. A bacterial challenge with A. hydrophila was conducted for 96 h. C. macropomum fingerlings that were fed with 400 and 800 mg L−1 of C. sinensis essential oil had the highest growth parameters, with final weights of 533.18 ± 2.03 mg and 531.91 ± 2.67 mg, respectively, and an increase in the number of thrombocytes, lymphocytes, monocytes, and neutrophils, as well as higher phagocytosis rates compared to the control group. Regarding the challenge, fish in the 400 and 800 mg L−1 treatments also exhibited the lowest cumulative mortality rate (26.66% ± 3.33%). Therefore, supplementation with C. sinensis essential oil promotes growth, improves health, and enhances resistance to A. hydrophila in C. macropomum fingerlings. [ABSTRACT FROM AUTHOR]

In this study, we analyzed the hematoimmunological effects of dietary supplementation with immunomodulators (β-glucans + nucleotides) and different levels of vitamins on Nile tilapia ( Oreochromis niloticus ) after exposure to physical stress. The following four diet treatments were used: diets with indicated vitamin levels (Vitind), diets with Vitind + immunomodulator (Vitind + Immune), diets with high vitamin content (Vithigh), and those with Vithigh + immunomodulator (Vithigh + Immune). The experiment included 560 fish in 28 tanks (20 fish tank -1 ), with seven replicates per treatment. After 60 days of supplementation, the water temperature was set at 20 °C, and complete biometrics were performed. The animals were then subjected to physical stress with temperature oscillations of 20 ºC to 30 ºC/30 ºC to 20 ºC/20 ºC to 30 ºC. Hematoimmunological data from 140 animals were collected post-stress. Antimicrobial titer and total plasma protein levels were significantly higher in fish not receiving immunomodulator-supplemented diets (2.88 ± 0.43 log2 and 26.81 ± 4.01 mg∙mL -1 , respectively) than in those that did. Conversely, the agglutination titer increased in fish fed with lower vitamin levels (3.33 ± 0.66 log2) compared to those with higher vitamin levels. Increased immunoglobulin levels were observed in fish fed diets co-supplemented with vitamins and immunomodulators, revealing an interaction between immunomodulators and dietary vitamin levels. In summary, the inclusion of immunomodulators in the diet enhanced the animals' resistance to physical stress and improved hematoimmunological parameters. Additionally, a high vitamin content in the diet did not modulate the immune responses in the animals., Competing Interests: Conflict of interests: DSC, ILP, SAPD, LC, PBM, LVPR, MCML, TAS, EY, UPP, JLPM and MLM – No conflict of interest