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This study evaluated the effect of short‐term baths with the essential oils (EOs) of Lippia sidoides, Ocimum gratissimum and Zingiber officinale on the survival, haematological, biochemical and histopathological parameters of native fish tambaqui (Colossoma macropomum), challenged with Aeromonas hydrophila. After challenge, the fish infected with A. hydrophila received therapeutic baths of 60 min, for five consecutive days. Treatments were as follows: challenged and not treated; challenged and treated with 10 mg L−1 of gentamicin; challenged and treated with EO of L. sidoides (2.5 and 5.0 mg L−1); challenged and treated with EO of O. gratissimum (5.0 and 10.0 mg L−1); challenged and treated with Z. officinale EO (5.0 and 10.0 mg L−1). The highest survival rates were 89.5% (fish treated with 5.0 mg L−1 of O. gratissimum EO) and 75.0% (fish treated with 5.0 mg L−1 of L. sidoides EO). Reductions in the haematocrit percentage, haemoglobin and erythrocyte number were observed in fish treated with L. sidoides and Z. officinale EOs compared with control fish. Mild to moderate damage to the liver tissue of fish after challenge and EO treatments were observed. It is suggested that baths containing O. gratissimum and L. sidoides EOs consist in a viable treatment to increase survival rates of C. macropomum infected with A. hydrophila. [ABSTRACT FROM AUTHOR]

The increase in the production and commercialization of aquatic organisms in Brazil is partly due to the growth of native species such as tambaqui. The intensification of fish farming systems has led to an increased occurrence of parasitic diseases, and this has become a serious issue, especially in fish farms in northern Brazil. The present study evaluated the use of albendazole and praziquantel in the control of Neoechinorhynchus buttnerae in tambaqui, in two separate trials. In the first experiment, six concentrations of albendazole (0, 100, 200, 300, 400, and 500 mg kg−1 diet) were evaluated, in triplicate, with 12 fish per tank, for 21 days. In the second experiment, using the same experimental design, fish were given five different doses of praziquantel (0, 4, 6, 8, and 10 g kg−1 diet). In both trials, control group were fed with commercial feed not medicated. Also, fish from each treatment (n=9) of both experiments were sampled and subjected to parasitological and hematological tests to determine the efficacy of the drugs. The prevalence of the acanthocephalans in fish was 100% in the albendazole trial, with no efficacy observed in 21 days. Prevalence of N. buttnerae in the praziquantel trial ranged from 66.7 to 77.8%, and efficacy varied from 0 (doses < 6 g kg−1 diet) to 59.01% (8 g kg−1 diet, respectively). There was no significant difference between treatments in both trials regarding hematological parameters. Further studies to determine the best treatment route, optimum dose, toxicity to fish, palatability, and any potential side effects are thus needed. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the antimicrobial activity of Lippia sidoides, Ocimum gratissimum and Zingiber officinale's essential oils against Aeromonas spp. isolates from Colossoma macropomum, and to determine their chemical composition. Essential oils were obtained through hydrodistillation and their chemical composition analyzed using gas chromatography coupled to mass spectrometry. The antimicrobial activity of the oils was evaluated by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The major compounds were thymol (76.6%), p-cymene (6.3%) and (E)- β-caryophyllene (5.0%) in L. sidoides; eugenol (43.3%), 1,8-cineole (28.2%) and β-selinene (5.5%) in O. gratissimum; and geranial (23.2%), neral (16.7%) and 1,8-cineole (15.8%) in Z. officinale. All the essential oils evaluated showed bactericidal action against isolates of Aeromonas spp., with MIC and MBC ranging from 625 to 5,000 μg mL−1. We highlight the L. sidoides oil with the best antimicrobial activity (MIC and MBC ranging from 625 to 1,250 μg mL−1). [ABSTRACT FROM AUTHOR]

The chemical composition of the essential oils of Mentha arvensis and Mentha piperita and their antimicrobial activity against twelve Aeromonas spp. isolates from tambaquis (Colossoma macropomum), an important native farmed fish species in Brazil, were evaluated. The oils were characterized using gas chromatography and mass spectrometry (GC/MS) and their antimicrobial activity was evaluated through the microdilution method. The essential oils of these Mentha species mainly comprised oxygenated monoterpenes (97.1% for M. arvensis and 86.2% for M. piperita) and menthol was the major compound of these oils (86.1% for M. arvensis and 33.8% for M. piperita). It was confirmed that these oils had antimicrobial activity against 12 isolates of Aeromonas spp., with minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) ranging from 1,250 to 16,666.7 μg mL−1. Better antimicrobial activity was achieved by the M. arvensis essential oil. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the antimicrobial activity of the essential oils from five Brazilian Piper species (Piper aduncum, Piper callosum, Piper hispidinervum, Piper hispidum and Piper marginatum) against strains of Aeromonas hydrophila, isolated from tambaqui (Colossoma macropomum), as well as their chemical composition. The oils were characterized by gas chromatography and mass spectrometry (GC/MS), and the major compounds identified were: dillapiole (80.7 %) for P. aduncum; safrole (67.0 %), methyl-eugenol (7.2 %) and β-pinene (6.6 %) for P. callosum; safrole (89.3 %) for P. hispidinervum; γ-terpinene (27.3 %), p-cymene (14.0 %) and α-terpinene (12.0 %) for P. hispidum; δ-3-carene (13.1 %), propiopiperone (8.0 %) and (E)-caryophyllene (6.8 %) for P. marginatum. The Brazilian Piper species evaluated in this study were able to inhibit the growth of the ten strains of A. hydrophila, with minimum inhibitory concentration (MIC) values ranging from 234.37 to 30,000 μg mL-1. The antimicrobial activity of Piper essential oils was considered strong for P. callosum, P. hispidinervum, P. hispidum and P. marginatum, with the exception of P. aduncum that presented weak activity for all strains. This is the first record of antimicrobial activity of Piper essential oils against strains of A. hydrophila isolated from tambaqui, suggesting the potential for use in the treatment of infections caused by this bacterium. [ABSTRACT FROM AUTHOR]