Hematological parameters of Mugil liza mullet submitted to different concentrations of formalin and freshwater

Abstract

Lebranche mullet, Mugil liza is a species of high economic value for fishing. Despite the importance of the species, little is known about the effects of therapeutic baths on the hematological parameters of mullet. Such parameters are important tools for facilitating the early detection of diseases and illnesses that may impair the performance of the animals. This study evaluated the hematological parameters of mullet submitted to therapeutic baths with formalin and freshwater. For the experiment a total of 108 mullets were used, divided in groups of six individuals per tank. In this experiment, immersion baths were tested for 1 hour in freshwater (zero salinity), formalin at concentrations: 150, 200, 250, 300 and 350 mg L-1 in seawater and a control (without formalin and parasitized), in triplicate. After the immersion bath, fish blood was collected from the caudal vein for evaluation of hematological parameters.  The blood was destined to erythrogram, leukogram, thrombogram and glucose determinations. The hematological analyses found significant difference in the number of erythrocytes, lymphocytes, hematocrit, hemoglobin, MCV, MCH, MCHC and glucose. However, there was no significant difference in thrombocyte, total leukocyte, monocyte and neutrophil values. It is concluded that 150 mg L-1 formalin concentration and freshwater bath for one hour can be used for mullet as it causes mild hematological changes.