Hematological and biometric traits of tuvira Gymnotus inaequilabiatus (Valenciennes, 1839) (Gymnotiformes: Gymnotidae) from the Brazilian Pantanal

ABSTRACT This study describes the hematological and biometric characteristics of male and female Gymnotus species from the Pantanal, Mato Grosso do Sul state, Brazil. Fifty adult specimens of Gymnotus inaequilabiatus were weighed, measured, and then euthanized. Blood was collected by puncturing the celiac mesenteric vein to determine the hematocrit, hemoglobin content, number of erythrocytes, mean corpuscular volume, mean corpuscular hemoglobin concentration, glucose level, absolute value of leukocytes, and relative value of leukocytes and thrombocytes. Body weight and relative condition factor did not differ (P > 0.05) between the sexes, as well as erythrogram and the blood glucose values. Hematocrit ranged from 18.0% to 54.0%; hemoglobin from 1.1 to 14.7 g dL-1; number of erythrocytes from 0.2 × 106 to 3.8 ×106 µL-1; MCV from 24.2 to 321.7 fL; and MCHC from 4.2 to 44.5 g dL-1. In the differential count were identified thrombocytes, lymphocytes, neutrophils, monocytes, basophils, immature leukocytes, and PAS-positive granular leukocyte (PAS-GL). Females had a higher percentage of immature leukocytes (P < 0.05) than males. Glucose levels, erythrogram, leukogram, and the morphology of defense cells are comparable to other fish species of the Pantanal. Thrombocytes were the most frequent defense cells, followed by lymphocytes and neutrophils.

First record of Trypanosoma sp. (Protozoa: Kinetoplastida) in tuvira (Gymnotus aff. inaequilabiatus) in the Pantanal wetland, Mato Grosso do Sul State, Brazil / Primeiro registro de Trypanosoma sp. (Protozoa: Kinetoplastida) em tuvira (Gymnotus aff. inaequilabiatus) no Pantanal, Mato Grosso do Sul, Brasil

The blood infection by Trypanosoma sp. in tuvira (Gymnotus aff. inaequilabiatus) from the Pantanal wetland was reported in this study. Ten fish from the Paraguay River in the Pantanal were evaluated for the presence of hemoflagellates. Trypomastigotes of Trypanosoma sp. were observed in blood smears from three fish (30 percent prevalence) and some forms were seen to be undergoing division. Using the diagnostic methods of fresh examination and blood centrifugation in hematocrit capillary tubes, the prevalence rate was 80 percent. This is the first report of Trypanosoma sp. in tuvira in Brazil.

O objetivo do presente estudo foi reportar a infecção por Trypanosoma sp. em tuviras (Gymnotus aff. inaequilabiatus) oriundas do Pantanal Sul-mato-grossense, Brasil. Dez peixes provenientes do rio Paraguai, Pantanal Sul-mato-grossense, foram avaliados quanto à presença de hemoflagelados. Tripomastigotas de Trypanosoma sp. foram observados nas extensões sanguíneas de três peixes (30 por cento de prevalência), e algumas formas encontravam-se em divisão. Por meio do exame a fresco e da centrifugação do sangue em capilar de hematócrito como métodos para diagnóstico, a taxa de prevalência foi de 80 por cento. Esse é o primeiro relato de Trypanosoma sp. em tuviras no Brasil.