Nitrite enters a fish culture system
after feed is digested by fish and
the excess nitrogen is converted
into ammonia, which is then
excreted as waste into the water.
Total ammonia nitrogen (TAN;
NH3 and NH4+) is then converted
to nitrite (NO2) which, under normal
conditions, is quickly converted
to non-toxic nitrate (NO3) by
naturally occurring bacteria
(Figure 1). Uneaten (wasted) feed
and other organic material also
break down into ammonia, nitrite,
and nitrate in a similar manner.