Ammonia in fish breeding systems and its effects on the water quality - A review

Abstract

Nitrogen is one of the most important elements of the metabolism of aquatic ecosystems, acting on the synthesis of proteins as a limiting factor of the primary productivity, and, eventually, as a toxic element to aquatic organisms. Total ammonium is composed by ammonium ion (NH₄⁺) and ammonia (NH₃). At high pH values, a higher proportion of toxic NH₃, in the form of total ammonium, is present. Food remains are the main source of dissolved nitrogen compounds in intensive fisheries. Ammonia, found at low levels at the beginning of the culture, when biomass is small, is a compound resulting from the protein catabolism. As biomass increases, the total ammonium level increases accordingly to the increase of the amount of food available. The control of the quantity and quality of food, as well as an adequate water flow control, are of fundamental importance to maintain a water of good quality in an artificial culture system. This review comments several papers emphasizing the important role of ammonia on the water quality of fish culture systems.