Abstract
The hematological parameters of fish contribute to the understanding of the health status in response to diseases, treatments, handling, and environmental factors. This study aimed to verify the hematological parameters of mullet Mugil liza after one-hour immersion baths in five concentrations of hydrogen peroxide (H2O2), an effective chemical treatment for several diseases in fish. A total of 108 fish (35.25 ± 6.09g) was distributed into six treatments with three replicates each: untreated fish (control), and fish treated with five concentrations of H2O2 (150, 200, 250, 300 and 350 mg L-1). Blood collection was performed immediately after bathing and 30 days after. Erythrogram, leukogram, thrombocytogram, hematocrit, plasma glucose, hemoglobin concentration and hematimetric indexes were analyzed. There was no significant difference in the erythrocyte and total leukocyte counts. Regarding plasma glucose and hematimetric indexes, the values were increased (p<0.05), except for mean corpuscular volume (MCV), that was decreased (p<0.05) after bath, including control. These responses may be associated to stress from handling and bathing procedure. In fish treated with H2O2, the number of thrombocytes and lymphocytes was lower (p<0.05) immediately after bath, while neutrophils and monocytes showed increased (p<0.05) values immediately after bath, which indicates adverse effects due to H2O2; however, these effects seem to be reversible after 30 days of recovery. The findings indicate that the exposure of M. liza juveniles to baths of 1 hour with up to 350 mg L-1 is safe, without significant risks in causing adverse physiological effects.
Keywords:
Marine fish farming; lebranche mullet; Mugilidae; treatment; hematology; H2O2
HIGHLIGHTS
Mullet (M. liza) juveniles were subjected to immersion baths with hydrogen peroxide;
Hematological parameters were analyzed immediately and 30 days after bath;
Exposure to H2O2 caused reduced MCV, lymphopenia, neutrophilia and monocytosis;
The effects of H2O2 were reversible after 30 days of recovery in clean water.