Effect of water temperature on aggressiveness and physiological parameters of juvenile matrinxã, Brycon amazonicus (Spix and Agassiz, 1829)

Daily rhythm of some blood parameters in two Amazonian fish, Astronotus ocellatus and Brycon amazonicus

“…In the present study, the absence of daily rhythm for glucose levels in A. ocellatus coincides with the results obtained for Oreochromis niloticus , another species of cichlid (Almeida et al, 2018) and Centropristis striata (Ren et al, 2020), as well as for Tinca tinca and Oncorhynchus mykiss when subjected to food deprivation (De Pedro et al, 2005; Polakof et al, 2007). For B. amazonicus , the observation of a daily glycaemic rhythm with acrophase at ZT = 04:16 ± 2:47 h may indicate the preparation for the greatest energy demand during the day, considering its high metabolic and behavioural activity that is predominant during daytime (Ferreira et al, 2020; Soares et al, 2008). These results are consistent with the findings of Guerra‐Santos et al (2017), which show higher glycaemic values in the period of greater locomotor activity in Oreochromis niloticus .…”

“…At the end of the experimental period, fish were anaesthetized with eugenol (64 μl/L), as indicated by Ferreira et al (2020), and immediately punctured in the caudal vein region to obtain blood samples with the aid of 0.8 ml disposable syringes containing heparin (5000 units/ml) as an anticoagulant. During the dark period, animal manipulation and blood collection were performed under low‐intensity red light (<0.3 lux) to avoid the effect of luminosity on physiological parameters, in accordance with Oliveira et al (2007).…”

“…However, there are fundamental problems in the production of this species, especially due to the stress state caused by the management that occurs in artificial systems, which in turn affects the reproduction, larviculture and growth of juveniles (Bernardino et al, 1993; Souza et al, 2014), compromising its production expansion in the Amazon region. Previous studies have evaluated physiological and behavioural responses of A. ocellatus (Muusze et al, 1998; Gutierre et al, 2016) and B. amazonicus (Lopes et al, 2018; Ferreira et al, 2020), resulting from exposure to different environmental factors. However, nothing is known about the existence of rhythms and the effect of the light–dark cycle on energy expenditure indicators for these two species of Amazonian fish of commercial interest.…”

“…Previous studies have evaluated physiological and behavioural responses of A. ocellatus (Muusze et al, 1998;Gutierre et al, 2016) and B. amazonicus (Lopes et al, 2018;Ferreira et al, 2020), resulting from exposure to different environmental factors. However, nothing is known about the existence of rhythms and the effect of the lightdark cycle on energy expenditure indicators for these two species of Amazonian fish of commercial interest.…”

Integration of satellite image–derived temperature and water depth for assessing fish habitability in dam controlled flood plain wetland

“…The relationship between top-down and bottom-up regulation of the food web is affected by water temperature, which affects biogeochemical cycle as well as growth of aquatic organism and abundance (Zimmerman et al 2020). Changes in thermal conditions in aquatic species cause physiologic or behavioural responses, according to numerous reports (Alfonso et al 2020;Ferreira et al 2020;Boukal et al 2019). Thermal stress, for example, can stifle aquatic organisms' development, affect their immune systems, or set off a chain of metabolic reactions that includes the production of heat shock proteins (Khan & Shahwar 2020;Tiwari et al 2020).…”