What Is Ammonia?
Ammonia is produced by fish when they excrete waste and is also produced when fish food or other organic matter decomposes in a system. Ammonia production is a normal and biologically necessary process in natural systems, but in man-made systems like aquariums or small ponds, it can easily become a problem if not carefully managed.
Ammonia is in its unionized form (NH3) is extremely toxic to fish in even the smallest quantities. It should be a fish keeper’s goal to have their ammonia level at or very close to zero at all times. One way you can tell that your ammonia levels may be elevated is by checking to see if your water is looking cloudy. This is a sign of a bacteria bloom which tends to arise in the presence of higher ammonia levels. A more accurate and safer method to check the ammonia levels is by doing a water test with a testing kit. I highly recommend doing this, especially when starting up a system. Ideally, once you add fish to your tank, you should never have any elevated levels of ammonia, but if you do, there are steps you can take to act quickly to save your fish from getting sick or dying.
What to do if Ammonia Levels are High
When dealing with elevated ammonia levels, the very first thing you should do is dose Seachem Prime (or Safe) every 1-2 days to your system, to protect your fish. This water conditioner temporarily detoxifies ammonia and nitrite which will temporarily help save your fish from getting sick or dying while you attempt to control the ammonia levels. Make sure to dose the conditioner as directed on the bottle. It may also be helpful to dose aquarium salt into the water as directed in my article about salt baths, to prevent nitrite poisoning (if the ammonia level is high, chances are the nitrite level is high too, which is also toxic). You can also do large volume water changes to immediately lower the concentration of ammonia in the system.
Reasons Why Ammonia Levels are High
One reason why your ammonia levels are elevated may be because you have not properly cycled your tank. This means you have not allowed your filters enough time or supplied them with enough ammonia and bacteria before adding fish to allow them to effectively handle the bioload of your fish. If this is the case, the best course of action is to continue to dose prime to detoxify the ammonia and nitrite and also add a large amount of bottled nitrifying bacteria. In doing this you will increase the rate at which nitrifying bacteria settles into the filter media and more effectively cycle your tank and filter system. Continue to dose prime and add additional bottled bacteria until ammonia levels reach near or at zero. During this time do not feed any food to the fish.
Another reason why the ammonia levels in your tank may be elevated is that your filter and circulation system are not adequate for the amount of bioload your system is producing. There are two solutions to this problem. You can either decrease the bioload of the system (decrease the amount of ammonia produced) or you can increase the filter size and rate of filtration to more effectively consume the ammonia.
How to Fix the Root Cause
To decrease your bioload, you can do one or multiple of the following: Reduce the amount of fish in your system, decrease the amount you are feeding the fish (overfeeding is a common cause for ammonia spikes), decrease the metabolism of the fish (this can be done by lowering the temperature), or increase the frequency and thoroughness of maintenance on the system, this means removing sludge, poop, and decaying matter from the substrate and filter system more often. Of these methods, removing fish and lowering the feeding rate are the two most effective at immediately and significantly decreasing the ammonia levels.
To increase the bioload capacity of your system, you can do one or multiple of the following: Increase the size of your filter, increase the number of filters, add more biological filter media to an existing filter, increase the circulation of the water in the system (by additional water pumps or additional airstones), adding fast-growing live plants to the system, or even by adding a gravel or sand bed (this adds additional surface area for beneficial bacteria to consume ammonia, however, this effect is not very significant). Of these methods, adding additional or larger filters is by far the most effective. All of these methods will increase the rate at which the ammonia in the water is circulated through filter media in which nitrifying bacteria can consume it.
Once you fix the root cause of the ammonia spike whether that be not having a properly cycled tank, having too large of a bioload, or not having enough filtration, then your system should be good to go. It may be helpful to always have some Seachem Prime and Seachem Stability on hand in case of another ammonia spike to quickly and safely handle it.