Ammonia in Aquarium: Symptoms, Causes & Ways to Check & Remove it

at 8:46 am

Ammonia can be a big problem for fish and fish keepers alike. It can quickly kill delicate fish species or it can make for a slow, painful death for more hardy fish species. Ammonia and nitrites alike can be managed properly with the proper equipment and know-how. In this brief article, we’ll familiarize you with the compound ammonia and how to get rid of it.

What is Ammonia?

Ammonia is a compound of Nitrogen and Hydrogen (NH3). In terms relevant to aquaria, ammonia is the direct result of fish osmoregulation (directly tied to fish respiration) as well as a product of anything organic that has been broken down by heteroptrophic bacteria. This could be fish food, a dead fish, a dead plant, and of course, fish excrement. Ammonia is toxic to fish. Even strong fish cannot tolerate its presence in the water for extended periods of time without sustaining permanent physical damage. Luckily, the answer to ammonia is a free one – bacteria. Specific ammonia oxidzing bacteria will break down ammonia just like other bacteria breaks down fish food and fish excrement. Once ammonia has been broken down (oxidized) it becomes Nitrite. It’s important to know that Nitrites are also quite toxic to fish. Not as quite as severe as ammonia but still dangerous. Again, nature provides the solution. Another species of bacteria specializes in breaking down (oxidizing) nitrites. Once nitrites have been broken down they become Nitrates. This process… from fish food to nitrates… is infamously recognized as the Nitrogen Cycle.

If you are interested in a more detailed understanding of the bacteria involved, you may find this article helpful.

How do I know if my aquarium has ammonia?

There is only one way to know for sure if you have ammonia in your tank – a test kit. There are several test kits commercially available exactly for this purpose. You should be able to buy them at a local pet store, or you can order them online from a vendor such as Foster and Smith. There are two main types of test kits, liquid kits, and dip strips. I do not recommend the dip strip variety. They can be contaminated easily and are very inaccurate. Still they are better than nothing and if, in a pinch they are all that is available you can use them. The liquid kits are much more reliable and accurate. I prefer to use the API Freshwater Master test kit. It allows you to test for Nitrates, Nitrites, Ammonia, and pH. In a properly cycled aquarium, you should never be able to detect ammonia or nitrites.

One thing is a certainty. If you just purchased an aquarium and added fish without properly preparing (cycling) the tank, you absolutely WILL have an ammonia problem. Test kit or not, you need to take steps now to protect your fish, picking up the necessary test kits at the earliest opportunity.

How did I get ammonia in my Aquarium?

There are several factors that can contribute to ammonia spikes. The most common reason for ammonia is skipping the cycle. The majority of new hobbyists unknowingly start up their first tank without first properly cycling it. This leads to a fast accumulation of ammonia and the subsequent initial fish deaths that drive so many beginners out of the hobby before they can really get into it. Basically, in an uncycled tank, all of the food, waste, and biological processes that occur naturally result in ammonia and without beneficial bacteria to break it down, the ammonia levels spike causing problems for your fish. To avoid this problem I recommend a fishless cycle.

Please become familiar with the basic concepts of the nitrogen cycle. It takes more than setting up a tank, filling it with water, and letting it run for a day or two. For the “cycle” to occur, there must first be ammonia, which is where the fishless cycle method comes into play.

Another cause for ammonia in your aquarium is a mini-cycle. A mini-cycle is a reference to an acute over abundance of nutrients that your current filter and or beneficial bacteria cannot accomodate. In other words you have either overloaded and overwhelmed the bacteria and they cannot process the ammonia fast enough, or your beneficial bacteria colony was somehow damaged and it can no longer shoulder the load it once was able to. A mini-cycle can be caused by adding fish to a tank, over feeding, by use of strong medications that have an adverse affect on beneficial bacteria, by performing water changes without using a dechlorinator, by a power outage that leaves a filter inoperable for long period of time, by under-filtration, by clogged filter media, or by insufficient water changes that result in “Old Tank Syndrome”. Anything that results in too much ammonia for the filter or current beneficial bacteria colonies to handle will result in a mini-cycle. The mini-cycle will complete once the bacterial colonies increase to a size sufficient to deal with the amount of ammonia present and/or being produced.

For clarity, a full on “Tank Cycle” is where beneficial bacterial colonies have to start from scratch. These types of cycles will take anywhere from 2 weeks to 8 weeks to complete. A mini-cycle is where bacterial colonies already exist and only have to increase in size. This type of cycle can complete anywhere from a few hours to a couple of weeks.

How can I remove Ammonia from my Aquarium?

The fastest way to reduce ammonia and nitrites is to do a large water change. A 50% water change will dilute the concentration of toxins in your aquarium by roughly one half. You should test for ammonia and nitrites before and after the water change. Your goal should be to bring the ammonia levels to as close to 0ppm (parts per million) as possible. This however, is a double edged sword. By bringing the ammonia levels down, you are effectively increasing your fish or fishes chance of survival and health. But at the same time, you are severely reducing the amount of nutrients available for beneficial bacteria to consume and grow. This will prolong the development of the cycle and may require several weeks of frequent large water changes. This is why we recommend completing the cycle before introducing any fish. You may need to temporarily test your water and/or do water changes 2-3 times per week to keep the concentration down until the underlying problem is solved.

Water Conditioners/Ammonia Removers

I want to quickly clarify something about Ammonia ‘removers’. They do not remove ammonia, they convert it into ammonium. Seachem Prime, Tetra AquaSafe NH/CL Formula, Jungle’s ACE, Kordon AmQuel, and Kent Professional Ammonia Detox can convert ammonia into non-toxic ammonium and the effects are only temporary (12-24 hours). This will keep your fish from getting ammonia burns while still allowing your biological filter to process the non-toxic ammonium into nitrites. If the water conditioner label doesn’t specifically mention that it neutralizes ammonia, then it won’t help. If you have ammonia present as a result of a mini-cycle or from a new cycle, I recommend Seachem Prime. It’s widely available and is a quality product. I don’t use Prime as a dechlorinator simply because I can buy a cheaper simple dechlorinator to do so. But I always keep a bottle on hand in case of emergencies.

Chloramine is another compound that you may find in your water. Most tap water sources today use trace amounts of Chlorine to help disinfect our drinking water. Some sources use Chloramine. Chloramine is less likely to dissipate before reaching the consumers tap, and is more chemically stable. All good and well except, Chloramine is essentially Chlorine + Ammonia. So if you have Chloramine in your tap water as a disinfectant, then you are adding ammonia to the tank. This is one of those situations where you are going to need a Dechlorinator/Ammonia remover. If you use a simple dechlorinator, it will break the bond between the ammonia and chlorine leaving ammonia free. Now you have to deal with the ammonia which is where the ammonia remover comes in. Prime will both ‘detoxify’ the chlorine, and convert the ammonia into ammonium removing the immediate threat to your fish.

Here’s another twist. Ammonium is not toxic to your fish, but your test kit will most likely read it as ammonia. Most liquid test kits use a Nessler reagent to measure the amount of ammonia in a sample of water. However, Nessler reagents pick up both Ammonia and Ammonium (NH3 and NH4) essentially giving you a false positive ammonia reading. If you have Chloramine in your tap water it would be prudent to purchase a Salicylate test kit. These tests will only pick up Ammonia and allow you to determine if you are having a mini-cycle instead of always getting a false positive ammonia reading after a water change.

Reducing Ammonia in an Aquarium – The process.

Beating ammonia poisoning can be a difficult task. Many fish species simply cannot tolerate its presence and the biggest problem is knowing when you have it. Ammonia is colorless so you can’t see it accumulate in your tank. The first step to beating ammonia is knowing it’s there. Buy a test kit. It is a vital tool for a new fish keeper and can absolutely save your fish’s life. When setting up a new tank, use the fishless cycling method. It’s a proven method and it saves fishes lives.

Ammonia ‘removers’ can also quickly bind ammonia into a non-toxic form relieving much of the stress and pain on your fish. Use it.

Let’s say that you have completed the cycle and have a mature bacteria colony, but something went wrong. A city wide power outage hit while you were at work and left your tank at home without power for 6 hours. The bacteria in your filters have had major die off from lack of oxygen flow and nutrients. The following day you test your tank water and find out you have ammonia.

  1. Water change. Depending on what concentration of ammonia you have, I recommend no less than a 50% water change as soon as possible.
  2. Prime. Dose the tank with Prime to detoxify the free ammonia.
  3. Add aquarium salt (Kosher salt/Canning salt). Use a dosage of 1 tablespoon per 5 gallons. OscarBeast wrote:Use of salt provides one unarguable benefit in that it can block the uptake of nitrite via the fish’s gills in an environment high in nitrite. The chloride ion in the salt is absorbed by the gills instead of the nitrite ion. This can be the difference between life and death for fish in a cycling tank.
  4. Keep in mind that salt does not evaporate. The only way it can be removed is through water changes much like Nitrates. After a water change, only replenish what you removed to maintain the recommended dosage. E.g. 100g tank fully dosed with salt (20 TBSP). After a 50% water change, replenish the salt dosage by adding 10 TBSP. Another reminder; some scaleless fish cannot tolerate the addition of salt. Some catfish, loaches and fancy plecostomus should not be exposed to salt
  5. Add an aerator/bubbler. Increasing oxygen levels in the water will make oxygen more readily available for your fish. Ammonia wreaks havoc on the soft tissues of the gills. It can become increasingly difficult for a fish to obtain oxygen when high levels of ammonia are present. A classic ammonia poisoning symptom is “gasping”.
  6. Repeat steps 1-3 as needed. Once your bacteria colony has recovered and you are no longer reading ammonia or nitrites and nitrates are within an acceptable range, you have won. Pat yourself on the back.

Bacteria in a Bottle

No article on combating ammonia in a aquarium would be complete without at least a brief discussion concerning “bacteria in a bottle”. Our hobby is infamous for the sale of products that simply do not work and nowhere is this more blatent than with the myriad of “bacteria in a bottle” products that flood the shelves of our local fish stores. Please allow me to save you some money. When combating an ammonia problem, unless the product is “Dr. Tim’s One and Only” or “Tetra Safestart”, don’t waste your time or your cash. Even with these two products, success is not a given. The best solution to resolving an ammonia problem is to stay ahead of it via the process defined above. Simple human effort to stay ahead of ammonia/nitrite reaching toxic levels by performing water changes and use of the proper chemicals (ammonia detoxifiers) to minimize the impact of ammonia on your fish in between water changes. But, if you can afford the expense, the two products I mentioned may be worth the effort (and cost) to at least minimize the “cycle time”. Other products are borderline worthless. Just remember, as long as the product is labeled “for ornamental fish only”, the legal definition is it only has to be designed to work. It does not actually have to work.


This has been a short, basic overview of Ammonia and some of its phases as they are relevant to the home aquarium. Understanding its effects and what steps to take to reduce its potency will save your fish. I hope we have provided you with another tool to keep a long lived and healthy home for your fishy friends.

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