 Ammonia in the pond water is a by-product of
metabolism by animals and bacterial
Decomposition of organic matter such as wasted
food, faeces, dead planktons etc.
 In water, ammonia nitrogen occurs in two Forms,
un-ionized ammonia and ammonium ion (NH4).
 Un-ionized ammonia is determined By total
ammonia concentration, ph, and water
temperature and to a lesser extent on salinity.
 It is considered more toxic form of ammonia due
to its ability to diffuse readily across cell
Membrane, hence should be less than 0.1 ppm.

 A given concentration of un-ionized ammonia
Is more toxic when dissolved oxygen
concentrations are low.
0.02-0.05 mg/litre Safe concentration
0.05-0.4 mg/litre Sub lethal effect
0.4-2.5 mg/litre Lethal effect

 Take 5 ml of water sample
 Add 1ml of trisodium nitrate
 Add 1ml of phenol nitro phosphate
 Add 1ml of sodium hyphochlorite
 Cover it with aluminium soil
 Keep at dark room for 2 hrs
 Observe it under spectro photometer at 630
nm

0
0.02
0.04
0.06
0.08
0.1
0.12
10:00 AM 12:00 PM 2:00 PM 4:00 PM
pond no 5
pond 7
pond 8
pond 11
wet lab
reservoir

 Maintaining sufficient level of Dissolved
oxygen
 periodic partial removal of algal blooms
 water exchange and addition of Liming
agents such as hydrated lime or quick lime
 Add zeolite to absorb obnoxious gas

 Nitrite is an intermediate product in
biological oxidation of ammonia to nitrate, a
process called nitrification
 Nitrite is highly toxic to fish as it oxidizes
hemoglobin to form methemoglobin, which is
incapable of transporting oxygen.
 Nitrite toxicity is affected by water pH and
the presence of chloride and calcium ions.
 Toxicity increases with increasing pH and
decreases with increasing calcium and
chloride concentrations.

 Optimum level of nitrite is less than 0.25
mg/L.
 Optimum level can be maintained by
effective removal of organic waste, adequate
aeration, correct application of fertilizer &
feed and use of biofertilizer to accelerate
nitrification.

 Take 50 ml of water sample
 Add 0.5 ml of sulphuramide solution
 Then 0.5 ml of diamine solution
 Obeserve the OD value at 543 nm

0
0.02
0.04
0.06
0.08
0.1
0.12
10:00 AM 12:00 PM 2:00 PM 4:00 PM
pond no 5
pond 7
pond 8
pond 11
wet lab
reservoir

 Correct stocking,feeding and fertilization
practices should be maintained
 Pond should kept well oxygenated
 Biofilteration should be done through special
filters by conversion of nitrite to harmless
nitrate occurs