In vivo exposure to high temperature compromises quality of the sperm in Colossoma macropomum

Increases in temperature can affect the reproduction of fish by decreasing the quality of gametes for fertilization. Therefore, this study aimed to evaluate the in vivo effect of temperature on the production and sperm quality of Colossoma macropomum, which is an economically relevant species for Brazil, and other countries. Broodstock were exposed for 10 days at temperatures of 29 °C (n = 4) and 35 °C (n = 4). After exposure, semen was collected and sperm quality was evaluated for kinetic, biochemical, morphological parameters, membrane integrity, and oxygen consumption. The sperm quality of males of specimens of C. macropomum exposed in vivo to the higher temperature was compromised and showed a difference in all the analyses (P < 0.05). Sperm showed decreased motility (51.9 ± 11.6 s) compared to the control (61.3 ± 5.5 s); curvilinear (CLV), straight line (SLV), and average path (APV) velocities decreased, and straightness (STR) and beat cross frequency (BCF) increased; oxygen consumption decreased (32.8 ± 3.4 pmol. (s.ml)⁻¹, picomol per second per ml) compared to the control (46.6 ± 3.5 pmol. (s.ml)⁻¹); and the activity of catalase (CAT) and glutathione S-transferase (GST) enzymes increased and decreased, respectively, in sperm from fish exposed to high temperatures. Furthermore, an increase in non-viable sperm with damaged membranes and sperm with altered morphology was observed. The observed alterations indicate that C. macropomum confined in environments with high temperatures possibly produces more sperm that are unviable for the fertilization process.