Catch‑and‑release: repetitive fishing, hematological variables and parasitism in the tambacu hybrid fish

Abstract

The objective of this work was to evaluate the hematological and parasitological responses of tambacu (Colossoma macropomum x Piaractus mesopotamicus) subjected to catch‑and‑release stress and to different stocking densities in a catch‑and‑release system. Two hundred and ten fish with mean initial weight of 785.33±152.02 g and mean total length of 34.43±2.21 cm were maintained in ponds and divided into three groups: without fishing and low density (G1), with fishing and low density (G2), and with fishing and high density (G3). No significant differences were observed between the mean values for hemoglobin concentration, erythrocyte number, differential counting of leukocytes, and glucose. The fish from the G3 group showed higher parasite and thrombocyte numbers, and lower weight gain and hematocrit. The activity of catch‑and‑release, associated with high stocking density, can disrupt organic balance and animal performance, favoring parasitosis.