What is Ammonia Poisoning in Fish Tank And How to Get Rid of It?

Ammonia Poisoning in Fish Tank is the condition when your aquarium’s level of ammonia and its related compound increase to the point where it becomes harmful to your fish. Mostly this problem occurs when you just started keeping fish. I also faced this issue ten years ago when I was first setting up an aquarium for my betta fish.

Although Ammonia Poison is not fatal to fish, you must take this issue seriously. The easiest way to treat ammonia poisoning is to change your water regularly with Ammonia-free water unless Ammonia count comes to a safe level. Let’s dig deeper to know more about Ammonia Poisoning and ways to treat it.


Ammonia poisoning is a typical tank disease that is seen when fishes are added to new aquariums without performing a complete nitrogen cycle. When the level of ammonia (NH3) or ammonium compounds (NH4+) increases in your tank, then your fish starts showing symptoms of ammonium poisoning. Sometimes the tap water can also contribute to ammonia poisoning. Ammonia poisoning can result in elevated pH value in the tank. The poisoning can also take place when your fishes are under medication, and the filter fails. This results in the death of bacterial colonies and decomposition of organic matter inside your tank. Even the small increase in ammonia level can infect your fish’s gills, whereas extremely high levels might be fatal. 

Ammonia Poisoning is also called ammonia stress. Usually, it is not called ammonia poisoning until a fish is dead. 


You cannot detect the presence of ammonia in the tank by your naked eye. You must perform a complete water test. In your nearby fish stores, you can easily get an ammonia test kit, pH test kit, etc. which can easily detect your tank condition. 


As we have mentioned earlier, ammonia is toxic to your fish; the only safe level of ammonia is 0 ppm (parts per million). Anything higher than that can be fatal to your fish. 0.25 ppm is often considered safe by many fish-keepers, but trust me, it isn’t. It might not be life-threatening but can damage the gills of your fish. So as soon as you detect a level of ammonia higher than 0 ppm, change the water immediately and perform a cycle. 


The leading cause behind the poisoning is probably your tap water. Many water companies use chloramine (chlorine bonded with ammonia) as a primary disinfectant in their water system. When you add this water to your tank and stockfish immediately without performing a nitrogen cycle, chances are your fish will get ammonia poisoning. This builds up a toxic ammonia and nitrogen environment in your tank that leads to organ infection and stress in fish. The nitrogen not only builds up but also displaces the oxygen, eventually suffocating the fish to death.

The other major component of ammonia poisoning is the decaying of leftover food in the tank. This causes a build-up of bacteria in the tank, which produces ammonia as a by-product. Sometimes fish themselves can also cause ammonia poisoning. When fish eat food, the protein building process can produce a by-product into their blood, which results in the seepage of ammonia in the tank through their gills. So even if you have applied all measures, sometimes it cannot be prevented at all.  


After the ammonia or ammonium compounds have displaced the oxygen in your tank, entirely or partially, your fish will go under a phase of uneasiness and suffocation called ammonia stress. The fish will show the following symptoms.

The initial symptoms:

  • The fish might appear to be grasping at the surface for air.
  • Fish will be lethargic due to loss in appetite or sometimes due to organ failure. 
  • In some cases, the fish might be laying eggs at the bottom with clamped fins.

The later symptoms:

  • As the poisoning continues, the fish tissues begin to deteriorate, shown by bloody patches on its body.
  • You might also notice hemorrhages on the fish either internally or externally.
  • You can see red or purple coloration on the fish gills and body. 


The immediate treatment that you can conduct when the ammonia level rises to 1 ppm is that you change 50 percent of water. You might also have to change water frequently within a short period to get the ammonia level below one ppm. For faster results, you can also use acidic products recommended by your vet to neutralize the ammonia. You must stop feeding the fish immediately to ensure that fish produce no more bioload in the tank. If the fish is heavily distressed, you may have to stop feeding it for several days.

In ammonia poisoning is severe I recommend you to keep the fish in a quarantine tank. Also, do not add more fishes until the tank is safe. Also, you must increase the power of your biofilter. Before adding the fishes back to your tank again, conduct an ammonia test, and only add fish when the level reaches approximately zero.

To sum up:

  • Move infected fish to a quarantine tank or hospital tank which doesn’t have ammonia infected water.
  • Change almost 50 percent of water in the tank and perform a fishless nitrogen cycle for a few days.
  • Check the ammonia level in the main tank 2-3 times a day. 
  • Finally, when the level reaches approximately 0 ppm, then you are safe to add fish. 


“Prevention is better than cure.” If you have a healthy, well maintained, clean, and happy tank, then your tank will never get ammonia poison in the first place. This will reduce half of our tension. Preventing your tank from ammonia poison and keeping fishes is not even that hard.  

The best and the correct way to prevent ammonia poisoning is to perform a complete nitrogen cycle before placing fish in the aquarium. The traditional nitrogen cycle can be lengthy and may take months to complete. But there is also a faster way for you to complete the cycle within three weeks. Just follow these steps:

  • During a new tank, setup, ask someone with a healthy and well-maintained tank for a cup of gravel from the bottom of their container. (be sure to check the ammonia level in their tank)
  • Place this cup of gravel at the bottom of your tank and cover it with new gravel that you have. 

The good bacteria present in the old gravel will help to complete the nitrogen cycle within three weeks. This reduces the number of toxic by-products in your tank. Finally, check ammonia level in your tank after a few weeks, and when the ammonia level reaches zero, finally add fishes. 

With that said, I don’t there are other ways to prevent ammonia poisoning. At any cost, do not overcrowd the tank. This leads to more bioload and is not good for your tank. Also, do not overfeed your fishes. If you see any food remains in the tank, immediately remove it within 5 minutes. 

Regular water change is very vital in preventing increased ammonia levels. Almost 10 percent of the water must be changed every week. The filter must always be running. Also, make sure that there are no dead plants or fishes in your tank.


Since we have discussed everything related to ammonia poisoning and stress, we can conclude that it is fatal. If it reaches to around one ppm and you still have not noticed it and applied preventive measure, then your fishes are done. So, as a good fish-keeper, check your tank for unwanted ammonia, clean it regularly, and do not overfeed the fishes to prevent ammonia poisoning. 


Image Credit: https://www.flickr.com/photos/koiquest10/25772662963