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 Increased ammonia levels in your aquarium or fish pond



1) Where does the ammonia in my tank come from?

·         Ammonia is added to the water by:

o   fish respiration (breathing).

o   breakdown of waste products (from plants, animals or food).

·         It can be present in two forms:

o   toxic un-ionised free ammonia (NH3) .

o   less toxic ammonium (NH4+).



2)Why do ammonia levels rise in an aquarium or pond?

 Ammonia levels rise in the tank when there is too much ammonia produced combined with insufficient numbers of nitrifying bacteria (bacteria that remove ammonia from water-Nitrosomonas or Nitrococcus) present in the pond/tank and filter.



3) How toxic to my fish is high ammonia in the water?

Even low levels of ammonia are toxic.


4) How do high levels of ammonia in the water affect my fish?

·         Affects your fishes’ ability to remove ammonia from their bodies.

o   This leads to the toxic build up of ammonia in the fish.

·         Ammonia is highly poisonousto the fishes’ cells.

·         Causesgill damage at low levels, leading to impaired gas exchange and suffocation.

·         Increases water absorption across the gillsleading to kidney failure.


5) What else affects the toxicity of ammonia?

High pH leads to increased toxic ammonia (NH3) levels compared to non-toxic (NH4+) in the water. 


6)  Why would ammonia levels rise in my aquarium or pond?

·         High levels of waste products in the tank from:

o   too high a stocking rate, too much food fed or increased plant waste material.

·         Low temperatures or low oxygen levels

o   affects the ability of the nitrifying bacteria to remove the ammonia.

·         New tanks, new or inadequate filter

o   do not have sufficient nitrifying bacteria.



7) How do I know I have high ammonia levels in my aquarium or pond?

You will need to test the water for ammonia levels. The water may look clear and clean yet still have high ammonia levels. Test kits are commercially available or your fish veterinarian can test the water for you. Always bring a separate container with a sample of the fishes’ water to the veterinary consultation to submit for ammonia testing.


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