Chart 1. Typical patterns of ammonia, nitrite and nitrate in a new aquarium.
The other complication that comes with ammonia's toxicity is the relative amount of free ammonia and ammonium ion. While ammonium ion may be toxic to marine fish, it is probably less toxic than free ammonia, and toxicity data are often reported only for the concentration of free ammonia. Aquarists should recognize, however, that such data may not be appropriate if the pH used in the test, or the situation to which it will be applied, deviates significantly from normal seawater's pH (as in a shipping bag, for example, whose pH may be well below pH 8.2, and whose toxicity may actually be coming from ammonium, and not the low concentration of free ammonia). Nevertheless, many scientific articles report ammonia toxicity in ppm (or mg/L) . It may also be reported as just ppm NH3.
Concentrations of ammonia that are not acutely lethal can still cause significant problems for fish. Salmon in seawater at pH 7.8, for example, show changes in white blood cells and various blood chemicals, and were more prone to disease, when exposed to sublethal concentrations of ammonia.15 Consequently, aquarists should strive to keep ammonia concentrations well below lethal levels.
My aquarium has ammonia, nitrites and nitrates in it already.
Ammonia & the Nitrogen Cycle: Keep Your Aquarium Healthy
Like all living creatures, fish give off waste products (pee andpoo). These nitrogenous waste products break down into ammonia (NH3),which is highly toxic to most fishes. In nature, the volume of waterper fish is extremely high, and waste products become diluted to lowconcentrations. In aquariums, however, it can take as little as a fewhours for ammonia concentrations to reach toxic levels.Some call it the biological cycle, the nitrification process, new tank syndrome or even the start-up cycle. They all are referring to the same cycle - The Nitrogen Cycle. The aquarium nitrogen cycle is a very important process for the establishment of beneficial bacteria in the aquarium and in the filter media that will help in the conversion of ammonia to nitrite and then the conversion of nitrite to nitrates. Check out the aquarium water chemistry page (on the left) for more information on these terms.The desired species of nitrifying bacteria are present everywhere(e.g., in the air). Therefore, once you have an ammonia source in yourtank, it's only a matter of time before the desired bacteria establisha colony in your filter bed. The most common way to do this is toplace one or two (emphasis on one or two) hardy andinexpensive fish in your aquarium. The fish waste contains theammonia on which the bacteria live. Don't overfeed them! More foodmeans more ammonia! Some suggested species include: common goldfish(for cold water tanks), zebra danios and barbs for warmer tanks, anddamselfishes in marine systems. Note: Do not use ``toughies'' or otherfeeder fishes. Although cheap, they are extremely unhealthy and usingthem may introduce unwanted diseases to your tank.Ammonia's toxicity to fish is very well know. Most aquarium and pond related books usually dedicate at least a paragraph or two on the subject. What is often not mention in many books is the relationship pH plays in the toxicity of the ammonia.