In vitro culture and morphology of Neoechinorhynchus buttnerae (Eoacanthocephala: Neoechinorhynchidae) collected from the intestine of tambaqui (Colossoma macropomum) farmed in the Brazilian Amazon.

The tambaqui (Colossoma macropomum) is a species of great economic importance for fish farming in the Brazilian Amazon, and acanthocephaliasis caused by Neoechinorhynchus buttnerae (Golvan 1956) represents an obstacle to its production due to it causing severe morphological damage to the intestinal mucosa, thus impairing the absorption of nutrients and causing weight loss in the fish. Therefore, the establishment of in vitro protocols for evaluation of anthelmintic drugs is the first step to development of effective measures for in vivo control of this endoparasite. The present study evaluated the in vitro survival of N. buttnerae maintained in Eagle's minimum essential medium under different culture conditions. Three assays were carried out to evaluate whether temperature, supplementation with the antibiotics penicillin and streptomycin, and culture medium replacement or no replacement would influence the motility and morphology of the acanthocephalans. The results of the Kaplan-Meier analysis indicated that the use of culture in minimum essential medium together with penicillin and streptomycin prolonged the parasite's survival when kept at temperatures of 24 °C or 28 °C. We describe herein for first time an alternative protocol that is ideal for the in vitro culture of N. buttnerae. As such, this protocol ensures greater reliability in further in vitro studies with N. buttnerae.

Acute toxicity of essential oils of Aloysia triphylla (L'Hér.) Britton, Lippia gracilis Schauer, and Piper aduncum L. in Colossoma macropomum (Cuvier, 1818).

The aim of this study was to determine the acute toxicity of the essential oils (EOs) of Aloysia triphylla, Lippia gracilis and Piper aduncum in juvenile tambaqui (Colossoma macropomum), and evaluate the possible histopathological alterations in their gills. For the acute toxicity tests, juvenile tambaqui (n=24/treatment) were distributed in six treatments with three replicates, which comprised the control and five EO concentrations of A. triphylla (60, 80, 100, 120 and 140 mg L-1), L. gracilis (35, 40, 45, 50 and 55 mg L-1) and P. aduncum (42.5, 45, 47.5, 50 and 52.5 mg L-1), with an exposure period of 4 h. The mortality rate and severity of damage to the tambaqui gills were proportional to the increase in the concentration of the EO, with LC50-4 h values estimated at 109.57 mg L -1 for A. triphylla, 41.63 mg L -1 for L. gracilis and 48.17 mg L -1 for P. aduncum. The main morphological damages observed in the gills of the tambaqui exposed to the three EOs, were Grade I: hypertrophy and hyperplasia of lamellar epithelial cells, lamellar fusion, epithelial detachment, capillary dilation and constriction, proliferation of chloride cells and mucosal cells and edema; in low frequency Grade II damage as epithelial rupture and lamellar aneurysm. Necrosis (Grade III damage) was observed only in gill lamellae exposed to P. aduncum EO (47.5, 50.0 and 52.5 mg L-1). Concentrations of EOs below LC50-4 h can be used sparingly, for short periods of exposure for the treatment of diseases in tambaqui breeding.

Antimicrobial resistance profile of Aeromonas spp. isolated from asymptomatic Colossoma macropomum cultured in the Amazonas State, Brazil.

Bacterial diseases are important factors that limit productivity in aquaculture. To reduce negative economic impacts, fish farmers use antimicrobials, often indiscriminately, and this action has led to bacterial resistance to drugs. The objectives of this study were to isolate and identify the main putative pathogenic bacterial species in tambaqui (Colossoma macropomum), establish the profile of resistance to antimicrobials by the methods of disc diffusion, and determine the minimum inhibitory concentration (MIC) values. Two hundred and ninety asymptomatic fish were collected between March and November 2015 from ten fish farms in the Amazonas state (Brazil). Of the total strains recovered from tambaqui, seven were identified as Aeromonas spp. by sequencing the 16S rRNA gene. These seven isolates showed resistance to ampicillin, 28% to erythromycin, and 28% to sulfonamide. Additionally, the seven isolates showed a MIC higher than the range evaluated for amoxicillin, penicillin, novobiocin, tylosin tartrate, and clindamycin, and 85% showed resistance to erythromycin. The results of this study indicate the need to increase the awareness of fish farmers and, most importantly, the government, about the lack of drug regulations for use in aquaculture, and good management practices, so the indiscriminate prophylactic and systemic use of antimicrobials be inhibited.

Uso do probiótico Efinol®L durante o transporte de tambaqui (Colossoma macropomum) / The use of probiotic Efinol®L during transportation of tambaqui (Colossoma macropomum)

Verificou-se a eficácia da adição de um probiótico potencialmente redutor de estresse, durante o transporte de juvenis de tambaqui (Colossoma macropomum). Os peixes foram transportados em sacos plásticos com probiótico (20mg/L) ou sem adição do produto à água. O transporte teve duração de 16 horas. Após o transporte, os peixes foram colocados em caixas de 150L para monitorar a recuperação por 96 horas. Para o monitoramento do estresse, avaliaram-se a glicose, o hematócrito e a hemoglobina, além das características de qualidade da água. Após o transporte, a glicose aumentou significativamente, permaneceu elevada nas amostras por 24 e 48 horas e retornou à concentração inicial, 96 horas depois, em ambos os tratamentos. A hemoglobina não se alterou durante e após o transporte, e o hematócrito aumentou significativamente no tratamento sem probiótico nos tempos 24 e 48 horas após o transporte. O probiótico utilizado não foi eficiente em suprimir as respostas de estresse em tambaqui durante o transporte, porém foi eficiente em suprimir as respostas pós-transporte.

The effectiveness of the addition of a potentially stress reducing probiotic during transportation of tambaqui juveniles was studied. Fish were transported with (20mg/L) and without probiotic in the water. The transport duration was 16 hours. After transportation, fish were placed in 150L tanks to monitor their recovery for 96-hours. The following stress parameters were evaluated: glucose, hematocrit, and hemoglobin, and also some water quality parameters. The responses of glucose presented similar pattern between the treatments. Glucose concentrations significantly increased after transportation, kept high for 24 and 48-hours after transportation, and returned to control-like concentration at 96-hours after transportation. Hemoglobin did not present significant difference during or after transportation. Hematocrit significantly increased in probiotic-free treatment at 24 and 48 hours after transportation. The stress response in tambaqui was similar between the tested treatments, indicating that the used probiotic was not efficient in suppressing the stress during transportation; however, it was able to mitigate post-transportation stress response.