Nitrogenous and phosphorus excretions in juvenile silver catfish (Rhamdia quelen) exposed to different water hardness, humic acid, and pH levels

Abstract

This study examined ammonia, urea, creatinine, protein, nitrite, nitrate, and phosphorus (P) excretion at different water hardness, humic acid, or pH levels in silver catfish (Rhamdia quelen) juveniles. The fish were exposed to different levels of water hardness (4, 24, 50, or 100 mg L(-1) CaCO3), humic acid (0, 2.5, or 5.0 mg L(-1)), or pH (5.0, 6.0, 7.0, 8.0, or 9.0) for 10 days. The overall measured nitrogen excretions were 88.1% (244-423 μmol kg(-1 )h(-1)) for ammonia, 10.9% (30-52 μmol kg(-1 )h(-1)) for creatinine, 0.02% (0.05-0.08 μmol kg(-1 )h(-1)) for protein, 0.001 % (0.002-0.004 μmol kg(-1 )h(-1)) for urea, 0.5% (0.64-3.6 μmol kg(-1 )h(-1)) for nitrite, and 0.5% (0.0-6.9 μmol kg(-1 )h(-1)) for nitrate, and these proportions were not affected by water hardness or humic acid levels. The overall P excretion in R. quelen was 0.14-2.97 μmol kg(-1) h(-1). Ammonia excretion in R. quelen usually was significantly higher in the first 12 h after feeding, and no clear effect of water hardness, humic acid levels, and pH on this daily pattern of ammonia excretion could be observed. Water hardness only affected the ammonia and P excretion of R. quelen juveniles in the initial and fifth days after transfer, respectively. The exposure of this species to humic acid increased ammonia excretion after 10 days of exposure but did not affect P excretion. An increase in pH decreased ammonia and increased creatinine excretion but did not change P excretion in R. quelen. Therefore, when there is any change on humic acid levels or pH in the culture of this species, nitrogenous compounds must be monitored because their excretion rates are variable. On the other hand, P excretion rates determined in the present study are applicable to a wide range of fish culture conditions.

<b>Water quality and survival rate of <i>Rhamdia quelen</i> fry subjected to simulated transportation at different stock densities and temperatures

“…High temperatures tend to speed up the metabolism of fish and, thus, result in greater release of solutes and nitrogen compounds in the water, reducing its quality. High concentration of ions in the water can cause stress (Golombieski et al, 2013) and lead to high mortality. Aside from temperature, other factors also affect dissolved oxygen levels.…”

“…Ammonia is the main product excreted by fish (Bolner et al, 2014), including R. quelen (Golombieski et al, 2013), and at high concentration compromises the metabolism, alters growth, and can lead to death (Cavero et al, 2004). Recently, Pottinger (2017) raised an issue that possibly ammonia, nitrate and nitrite influence the function of the stress axis in fish, alone or in combination.…”

Growth, water quality and oxidative stress of Nile tilapiaOreochromis niloticus(L.) in biofloc technology system at different pH

“…Besides harming to the functioning of BFT system operation, the pH oscillations can represent physiologic challenges to fish. The decrease in pH has been related to disturbances in acid‐base balance, increased of gill permeability and consequent ionic loses and water absorption (Wood, ), besides the alteration on ammonia excretion (Golombieski et al, ) and oxidative stress (Mai et al, ).…”

“…The decrease in pH has been related to disturbances in acid-base balance, increased of gill permeability and consequent ionic loses and water absorption (Wood, 2001), besides the alteration on ammonia excretion (Golombieski et al, 2013) and oxidative stress (Mai et al, 2010).…”

Net ion fluxes and ammonia excretion during transport of Rhamdia quelen juveniles

“…The high transport cost request the use of a small amount of water and the highest load density possible, which cause accumulation of metabolites and deteriorate water quality (GOLOMBIESKI et al, 2003). Ammonia is the dominant end product of nitrogen metabolism in most teleosts, including silver catfish (GOLOMBIESKI et al, 2013), and is toxic at low concentrations (IP & CHEW, 2010). During transport the concentration of this metabolite increases and may be a potential risk that influences fish survival and duration of transport (GOMES et al, 1999;GOLOMBIESKI et al, 2003;CARNEIRO et al, 2009).…”