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 × 10 6 to 3.8 ×10 6 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.

Application of haematology parameters for health management in fish farms

“…Basophils are the least abundant granular cells in fish blood. Their distribution is similar to that of eosinophils, and they also mainly exist in the head kidney, and spleen, with very little content in peripheral blood 268 . Basophils are typically round and sometimes have bluntly rounded pseudopods on the surface.…”

“…Their distribution is similar to that of eosinophils, and they also mainly exist in the head kidney, and spleen, with very little content in peripheral blood. 268 Basophils are typically round and sometimes have bluntly rounded pseudopods on the surface. The nucleus is semicircular or bean-shaped and located on one side of the cell.…”

Erythrocyte parameters and condition factor of Gymnotus spp. (Gymnotiformes: Gymnotidae) under culture conditions

“…The values of red blood cells for Gymnotus sp varied, which may be due to nutritional factors and age, since the animals sampled were of different ages. However, they remained within the reference standards for the species (Rodrigues et al, 2018). However, nutritional status, age, and environmental conditions are the main factors responsible for the changes in the erythrocyte count of fish (Tavares-Dias & Moraes, 2004;Ranzani-Paiva et al, 2013).…”