Growing in the Dark Warmth: The Case of Amazonian Fish Colossoma macropomum

Abstract

Photoperiod is considered an important synchronizer of biological activities and endocrine pathways, including growth. As ectotherms, fish have many physiological functions controlled by the photoperiod. However, the combined effects of photoperiod and temperature should be clarified, particularly for tropical fish living near their upper thermal limit, as is the case of Amazonian fish. The central aim of this study was to evaluate the combined effect of photoperiod and temperature on growth and physiological aspects of tambaqui (Colossoma macropomum). Juveniles of tambaqui were distributed in 70 L tank, following a factorial design that included three photoperiods (light 0 h: darkness 24 h; light 12 h: darkness 12 h; and light 18 h: darkness 6 h) associated with three temperatures (26, 29, and 32 • C). They were maintained under these conditions for 2 months. Fish reared in the dark at 29 and 32 • C showed better performance compared to fish reared under extended light conditions at all temperatures. Among physiological responses, it has been observed that blood parameters tend to be disturbed with increasing temperature and that extended light conditions at low temperatures caused similar effects on the analyzed fish, suggesting blood hemoconcentration. Fish under extended light conditions showed an increase in glucose, cortisol, cholesterol, and total proteins, indicating additional physiological disturbances. In conclusion, our study shows that, unlike marine and temperate fish, C. macropomum, a fish species endemic to the Amazon, grows better in warmth dark, showing no significant physiological disturbances, similar to observations described for wild animals of this species. Our results support that changes in fish growth occur in response to environmental conditions. Therefore, fish species from freshwater, estuarine, and marine environments, must be specifically analyzed regarding the combination effects of photoperiod and temperature.

Growth performance and health of juvenile tambaqui, Colossoma macropomum , in a biofloc system at different stocking densities

“…The importance of water temperature to BFT is associated with its influence on the microorganism formation and stabilization time, as well as the environment maintenance (Hostins et al, 2015). In the present study, water temperature (25.87 ± 0.13 to 27.37 ± 0.05°C) was lower than those considered ideal (29–32°C) for tambaqui (Amanajás et al 2018), suggesting potential increase in fish performance at higher temperatures such as in outdoor infrastructures.…”

“…for tambaqui (Amanajás et al 2018), suggesting potential increase in fish performance at higher temperatures such as in outdoor infrastructures.…”

Effect of carvacrol on the haemato‐immunological parameters, growth and resistance of Colossoma macropomum (Characiformes: Serrasalmidae) infected by Aeromonas hydrophila

“…Haematological parameters, that is, RBC, Hb, Ht, MCV, MCH and MCHC, are used as indicators of fish nutritional and health status (Amanajás et al, 2018). In general, carvacrol has no effect on erythrocytic indexes in fish (Ahmadifar et al, 2014; Yilmaz et al, 2015).…”

The Biofloc system potential in reducing dietary protein levels for tambaqui

“…A total of 360 tambaqui juveniles (9.20 ± 0.23 g) were distributed in a completely randomized 2 x 3 factorial design applied to two rearing systems, BFT and CW, and three feed crude protein (CP) levels, 32, 28 and 24% in triplicates. Eighteen 400-L circular polyethylene tanks (experimental units -EU) at a density of 50 sh.m − 3 , under constant aeration and lidded to reduce light entry (Amanajás et al, 2018). The study was carried out according to the Brazilian animal welfare standards and International Organization for Standardization guidelines (2006), approved by the Ethics Committee INPA (protocol nº Prot.…”