A broader look at ammonia production, excretion, and transport in fish: a review of impacts of feeding and the environment

Abstract

For nearly a century, researchers have studied ammonia production and excretion in teleost fish. Stemming from past investigations a body of knowledge now exists on various aspects including biochemical mechanisms of ammonia formation and specific routes and tissues used for ammonia transport, culminating in a current detailed theoretical model of branchial transport, including the molecular identities of the moieties involved. However, typical studies examining ammonia balance use routine laboratory conditions and fasted fish. While avoiding additional variables that influence nitrogen balance, these studies are arguably idealistic and do not reflect the natural variety of conditions that fish encounter. Further studies have revealed the impacts of extrinsic factors (e.g. salinity, pH, temperature) on ammonia handling in fasted fish whereas others have explored intrinsic factors, such as life history and developmental impacts. One routine challenge for ammonia balance that fish encounter is feeding and digestion. Fortunately, many new studies have revealed the impact of feeding and digestion on several aspects of ammonia balance; from production to excretion and to transport, and several have done so incorporating supplemental extrinsic and/or intrinsic factors. Together, these complex studies reveal realistic responses to multifactorial challenges encountered by animals in the wild and begin to provide a holistic view of ammonia balance in freshwater teleost fish.

Koi sleepy disease as a pathophysiological and immunological consequence of a branchial infection of common carp with carp edema virus

“…In the present study, increased ammonia levels were observed in carp under KSD, like it is initially noted in the serum of carp under hypoxia or starvation as well [ 34 ]. Ammonia excretion in freshwater fish occurs at a proportion of 80–90% across gills epithelia, while kidney, skin or gut account for the remainder [ 35–37 ]. The changes to gill anatomy in carp affected by KSD might result in an impairment of ammonia excretion and subsequent elevated body ammonia levels.…”

Feed management and stocking density for larviculture of the Amazon ornamental fish L333 king tiger pleco Hypancistrus sp. (Siluriformes: Loricariidae)

“…The increase in total ammonia has been associated with reduced growth in the larviculture of Nannostomus beckfordi (Abe et al., 2019); however, a similar association was not observed during the larviculture of the Neotropical fish species Lophiosilurus alexandri (Cordeiro et al., 2016), Brycon amazonicus (Barros et al., 2019) and Rhinelepis aspera (Santos et al., 2012). It is important to monitor the levels of intoxication for each species, which may vary and induce chronic stress and growth reduction (Bucking, 2017; Zhang et al, 2019. In general, the values obtained in the present study were too low to induce toxic effects (Moro et al., 2013).…”

Changes in metabolic rate, excretion, energy reserves, and starvation response of diploid and triploid Salvelinus fontinalis and diploid O. mykiss after long-term exposure to elevated temperature

“…A positive relationship between nutrient digestibility and temperature has also been observed in studies on S. salar (Bogevik et The excretion of dissolved ammonium (NH 4 -N) and total nitrogen bound did not differ between 2n and 3n S. fontinalis and 2n O. mykiss acclimated to 9°C and exposed to 20°C for 32d. Increased ammonium excretion would be an indication for increased protein catabolism either due to higher amount of feed uptake or due to catabolism of muscle tissue (Bucking 2017). Also, other studies on O. mykiss found no differences in ammonium excretion in relation to temperature (Forsberg and Summerfelt 1992;Azevedo et al 1998).…”