Author:

Abstract:

Since a few years, burbot has been introduced as a new aquaculture species in Belgium for both flowthrough and recirculating aquaculture systems (RAS). While this fish species can be successfully cultured in RAS, its tolerance towards ionized ammonium (NH4+) and nitrate (NO3 -) is unknown. The effects of toxic un-ionized ammonia (NH3) are well-studied for several aquaculture species, but the chronic effects of elevated ionic NH4+ concentrations are unknown. Low concentrations of NO3- are regarded as non-toxic to fish. However, the tolerable NO3- concentration is species-specific. Chronic exposure to high levels of NO3- can cause negative effects in fish, such as stunted growth. The tolerable threshold for NO3- for burbot isunknown. In order to adequately dimension the biological filter capacity and the required amount of water exchange for a commercial farm, it is crucial to identify the maximum tolerable NH4+ and NO3- concentrations for this species. We conducted two experiments in order to evaluate the effect of elevated NH4+ and NO3- concentrations on burbot growth performance and mortality.