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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]

This study assessed the in vitro anthelmintic activity of eugenol, thymol and tannic acid against the acanthocephalan endoparasite Neoechinorhynchus buttnerae. Tambaqui fish Colossoma macropomum intestines were collected and dissected for parasite removal. The anthelmintic activity of the compounds studied was tested in vitro using minimum essential medium (MEM) to maintain parasite viability. One control group and from 8 to 10 treatments were carried out in triplicate. Ten N. buttnerae specimens were introduced to each MEM plate, and after exposure to the compounds, parasite motility was observed every 15 min. The LC50 value of eugenol after 2, 6 and 24 h exposure was 1.01, 0.79 and 0.41 mg.mL-1, respectively; to thymol the values were 1.97, 0.96 and 0.92 mg.mL-1, and to tannic acid were 4.68, 1.79 and 1.30 mg.mL-1. Among the compounds tested, eugenol was the most efficient against N. buttnerae, eliminating 100% of the parasites after 15 min exposure to the three highest concentrations tested (1.56, 3.125 and 6.25 mg.mL-1). Thymol eliminated over 90% of the parasites after 2h exposure to the three highest levels tested (0.78, 1.56 and 3.125 mg.mL-1), and tannic acid showed the lowest activity, eliminating 100% of parasites after 6h exposure to doses between 6.25 and 50 mg.mL-1. [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]

Neoechinorhynchus buttnerae is the only acanthocephalan species that has been detected infecting tambaqui (Colossoma macropomum) in northern Brazil. This helminth greatly affects nutrient uptake in fish and leads to cachexia and economic losses of up to 100% in tambaqui production. This study investigated the efficacy, in vitro and in vivo, of a food additive (Acantex) to control N. buttnerae in tambaqui, as well as its effects on fish blood parameters and possible effect on monogeneans. For the in vitro assay, the parasites were exposed to nine concentrations (1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5 and 5.0 mg/kg) of Acantex and one control (without the product). For the in vivo assay, 120 naturally infected tambaqui were distributed into twelve tanks (10 fish per tank) and were divided into four treatments, in triplicate. Fish were fed with commercial feed containing 0.0, 3.0, 4.0 and 5.0 mg/kg of Acantex, for 25 days. Acantex at 3.0 mg/kg showed 100% efficacy against N. buttnerae in in vitro testing, after exposure for 2 hr. In vivo efficacy was 13.46% at 3.0 mg/kg against the endoparasite N. buttnerae and caused a mortality rate of 19%–37% of monogeneans. Blood and biochemical parameters suggested that fish were malnourished due to attached intestinal parasites and the resulting competition for nutrient uptake. Acantex did not show adequate efficacy in treating acanthocephalosis under the conditions of this study; therefore, more efficient forms of Acantex administration in the diet of tambaqui are warranted to eliminate acanthocephalans. [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]

This study investigated the in vitro efficacy of essential oils (OEs) of four species of plants of the family Piperaceae, these being; Piper hispidinervum, Piper hispidum, Piper marginatum and Piper callosum, in the control of Neoechinorhynchus buttnerae acanthocephalus that affect tambaqui. The tested concentrations of OE were: 0.19; 0.39; 0.78; 1.56; 3.125; 6.25; 12.5; 25 and 50 mg.mL-1, in triplicate, into petri dishes containing 10 parasites per plate. In this in vitro assay, all OEs studied showed significant activity against the acanthocephal N. buttnerae. There was higher mortality of the parasites at the highest concentrations and times of exposure to the OEs tested. Effective concentrations of 50% (EC50) were obtained through probit analysis and evaluated according to the exposure time in 2, 6 and 24 hours. The OE of P. hispidinervum showed lower values of EC50 (0,56; 0,54 e 0,51 mg.mL-1) compared to the values obtained for Piper hispidum (EC50 de 5,44; 3,85 e 1,75 mg.mL-1), Piper marginatum (EC50 de 2,98; 1,3 e 1,27 mg.mL-1) and Piper callosum (EC50 de 2,66; 2,16 e 2,16 mg.mL-1). [ABSTRACT FROM AUTHOR]

The antimicrobial activity of the essential oils from Lippia alba, Lippia sidoides, Mentha piperita, Ocimum gratissimum and Zingiber officinale was tested against Streptococcus agalactiae. The major compounds in the oils, identified by gas chromatography and mass spectrometry (GC/MS), were geranial (25.4%), neral (16.6%) and caryophyllene oxide (16.0%) in L. alba; thymol (76.6%), p-cymene (6.3%) and β-caryophyllene (5.0%) in L. sidoides; menthol (30.5%), menthyl acetate (14.6%), pulegone (14.2%) and menthone (12.9%) in M. piperita; 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 essential oils evaluated showed bactericidal action against S. agalactiae with minimum inhibitory concentration (MIC) ranging from 312.5-2,500 μg mL−1 and minimum bactericidal concentration (MBC) ranging from 416.7-2,500 μg mL−1. In this study, L. sidoides essential oil showed the better results against S. agalactiae. [ABSTRACT FROM AUTHOR]

In the creation of tambaqui (Colossoma macropomum) intestinal endoparasites has been calling attention to the increase of cases in fish farmed in northern Brazil. This study investigated the in vitro efficacy of essential oils (OEs) of four species of plants of the family Piperaceae, these being; Piper hispidinervum, Piper hispidum, Piper marginatum and Piper callosum, in the control of Neoechinorhynchus buttnerae acanthocephalus that affect tambaqui. The tested concentrations of OE were: 0.19; 0.39; 0.78; 1.56; 3.125; 6.25; 12.5; 25 and 50 mg.mL-1, in triplicate, into petri dishes containing 10 parasites per plate. In this in vitro assay, all OEs studied showed significant activity against the acanthocephal N. buttnerae. There was higher mortality of the parasites at the highest concentrations and times of exposure to the OEs tested. Effective concentrations of 50% (EC50) were obtained through probit analysis and evaluated according to the exposure time in 2, 6 and 24 hours. The OE of P. hispidinervum showed lower values of EC50 (0.56; 0.54 e 0.51 mg.mL-1) compared to the values obtained for Piper hispidum (EC50 de 5.44; 3.85 e 1.75 mg.mL-1), Piper marginatum (EC50 de 2.98; 1.3 e 1.27 mg.mL-1) and Piper callosum (EC50 de 2.66; 2.16 e 2.16 mg.mL-1). [ABSTRACT FROM AUTHOR]

Phytotherapy can replace antibiotic administration as an alternative to control Aeromonas hydrophila, one of the main bacteria involved in the aetiology of farmed fish diseases. Given that plants of the Lippia spp. genus show biological potential for antimicrobial activity, this study evaluated the chemical composition of essential oils extracted from Lippia alba, Lippia origanoides and Lippia sidoides and their activity against A. hydrophila. The oils were obtained by steam distillation in a Clevenger-type apparatus and their composition determined by gas chromatography and mass spectrometry (CG/MS). Antibacterial activity was assessed by calculating the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) using broth microdilution method. The main compounds identified were geranial (25.4%) and neral (16.6%) in L. alba oil, carvacrol (40.4%) and p-cymene (11.4%) in L. origanoides oil and thymol (76.6%) and ortho-cymene (6.3%) in L. sidoides oil. The three Lippia species showed bacteriostatic and bactericidal action against A. hydrophila, with MICs and MBCs ranging from 1250 to 5000 μg mL−1. Of the species tested, the best performance was obtained with essential oil of L. sidoides. [ABSTRACT FROM AUTHOR]

The aim of this study was to molecularly identify different species of Aeromonas isolated from farmed tambaqui (Colossoma macropomum) from North Brazil, and evaluate their pathogenic potential by the presence of virulence genes. From the extraction of bacterial DNA, PCR (polymerase chain reaction) of the primers 16S rDNA, aerA (cytolytic enterotoxin), ast (cytotoxic enterotoxin) and act (cytotoxic enterotoxin) were performed. Of 24 isolates evaluated, eight amplified the ast gene, one amplified the act gene, but the areA gene was not amplified in any isolate. Sequencing of the 16S rRNA primer revealed a predominance of Aeromonas jandaei specie (92%). Aeromonas taiwanensis (4%), for the first time isolated from fish in Brazil, and Aeromonas hydrophila (4%) each appeared as just one isolate. Results showed that 32% of Aeromonas isolated from farmed tambaqui have considerable pathogenic potential for systemic damage, since the selected PCR primers are encoding the most common virulence genes in Aeromonas with high pathogenic intensity. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the anesthetic potential of the essential oils of Aloysia triphylla (EOAT), Lippia sidoides (EOLS) and Mentha piperita (EOMP) in relation to juvenile tambaqui (Colossoma macropomum), based the swimming behavior of these fish and possible histopathological damage to the gills. To induce anesthesia, juvenile tambaqui (130.55 ± 22.4 g; 16.8 ± 0.95 cm) were individually exposed to different concentrations of the essential oils (EOAT: 5, 10, 20, 40, 60, 80 and 150 mg L−1; EOLS: 2, 5, 10, 20, 30, 40 and 50 mg L−1; EOMP: 5, 10, 20, 40, 60, 70 and 90 mg L−1), for exposure periods of between four minutes and six hours. The three essential oils evaluated presented anesthetic properties. The concentration intervals over which the fish reached all the stages of anesthesia (1, 2, 3a, 3b and 4) were between 40 and 150 mg L−1 for EOAT; 20 and 50 mg L−1 for EOLS; and 40 and 90 mg L−1 for EOMP. The times taken to reach the anesthesia stages were inversely proportional to the increases in the concentration of the essential oils. The histopathological damage to the gills of the tambaqui that resulted from using essential oil concentrations that were defined as anesthetic (150 mg L−1 EOAT, 30 mg L−1 EOLS and 90 mg L−1 EOMP) were also evaluated. The main damage recorded was hypertrophy and hyperplasia of the lamellar epithelium, lamellar fusion and proliferation of chloride cells. According to the histopathological alteration index (HAI), there were no irreversible damage (such as fibrosis and necrosis) to the gills of the tambaqui. However, while EOLS and EOMP caused mild damages in the gills, the EOAT generated more severe damages. Overall, for the tambaqui, the essential oils of A. triphylla, L. sidoides and M. piperita are efficient anesthetic in the doses of 150, 30 and 90 mg L−1, respectively. • This study reports the sedative and anesthetic effects of Aloysia triphylla , Lippia sidoides and Mentha piperita essential oils on Colossoma macropomum. • The essential oil of L. sidoides (30 mg L-1) induced faster anesthesia and recovery in C. macropomum. • Essential oils of A. triphylla , L. sidoides and M. piperita caused no irreversible damage to the gills of C. macropomum. [ABSTRACT FROM AUTHOR]