Ammonia
Ammonia is introduced into aquaculture ponds via feeds, aquatic animal
excretion, and biological degradation of unconsumed feeds. Ammonia is available in
water in two forms of NH3 or NH4
+
depending on pH of water. Free ammonia (NH3) is
more toxic towards aquatic animal in comparison to ionized form (NH4
+
). The proportion
of free ammonia increases with increasing pH and increasing temperature. Toxic
concentrations of ammonia can damage gills of fish, consequently impairing its respiratory
system. Ammonia also causes neurological and cytological failure in fish. The acceptable
level of ionized ammonia (NH4
+
) is 1.0 mg N/L