Haematology and acute inflammatory response of Oreochromis niloticus (Osteichthyes: Cichlidae) submitted to a single and consecutive stress of captura

Abstract

This work evaluated the effects of two different intensities of 30 s stress of emersion on the hematological and inflammatory response in the swim bladder of Oreochromis niloticus. Fish were acclimated for 10 days, distributed in 4 treatments: injection with 0.5 mL of sodium chloride solution 0.65%, 500 µg carrageenin, 3 mg LPS/kg body weight and non-injected; 3 experimental groups constituted by a single stress (SE), consecutive stress (CE) in which the stress was applied 4 times every 60 min and non-stressed fish (NS) with 3 replicates. There was no change in the plasma cortisol concentration, total leucocytes number and hematocrit after SE, CE and NE. On the other hand, CE provoked significant increasing in glucose of all treatments. In fish submitted to SE and CE increased erythrocytes number after carrageenin and LPS injection was observed. Increased neutrophil percentage and decreased lymphocyte percentage were the main characteristics observed in the differential counting of leucocytes after CE. Moreover, carrageenin and LPS injected fish showed the highest leucocytes number in the inflammatory exudate in comparison to saline injected. Tilapia showed different response when submitted to the same stress in comparison to previously evaluated Piaractus mesopotamicus and the hybrid tambacu.