In intensive land-based or cage cul

In intensive land-based or cage culture systems, there is a con-tinuous production of ammonia depending on the diet used,
feeding procedures and general rearing conditions [7,15].
Ambient ammonia may reach high levels especially in inte-grated culture systems using re-circulated water (up to 70%
water re-use), and/or in marine cages or enclosures supplied
by water of poor quality caused by accidental or chronic pol-lution (sewage effluents, industrial or agricultural wastes). In
these cases, ammonia acts as a limiting factor for fish growth
or survival. A serious type of water pollution, which is primar-ily originated from agricultural drainage containing fertilizers
and growth stimulants as well as from air-borne nitrogenous
compounds that comes from automobile exhaust, industrial
pollution and ammonia from manure, has been considered
the most widespread pollution problem facing aquaculture
and freshwater systems