Last Updated on 2026-06-11
When setting up an aquarium, water quality is probably one of the most important things to keep an eye on. There are a lot of things that can hurt the health of your fish, like low oxygen levels, unstable water, and a high pH, but nothing is as dangerous as high ammonia levels. Ammonia is dangerous because when it gets too high, you won’t know right away until your fish shows signs of being poisoned by it. But ammonia is easy to deal with, and it’s also easy to stop it from getting out of hand. We’ll talk about everything you need to know about ammonia in this article.
What Is Ammonia?
When people talk about keeping fish, the word “ammonia” always comes up. Ammonia is a common chemical that can be found in all aquariums with living, breathing animals. But there is more to that than being just a chemical in our aquariums.
Ammonia is an inorganic chemical that builds up in aquarium tanks as a result of the life that is thriving in your fish tank. It is odorless and colorless and might not do anything in your tank in small amounts, but it can quickly build up and cause harm to your fish and even lead to death. If fish are exposed to too much ammonia, they can get sick or even die.
To keep fish healthy and safe, it is important to keep ammonia levels from getting too high. Try not to put too many fish in your tank, and give them the right amount of food. It’s better to stop spikes in ammonia than to try to fix them.
What Are The Signs That Ammonia Levels Are Too High?
Ammonia spikes, which is a sudden jump in the amount of ammonia in the tank, are dangerous because they do not show visible signs. But it has an effect on all the fish in the tank, which you can tell by watching them. Here are some signs and symptoms that could mean that the amount of ammonia in your tank is getting too high.
1. Increased Mucus Production
When fish make more mucus, it can also mean that they are living in a stressful place. If you can’t find anything in your fish tank that could be making the fish stressed, it’s likely that the water has a lot of ammonia.
2. Bleeding Gills
Ammonia burns and irritates the gills of the fish, making it inflamed and swollen. In extreme cases, ammonia can cause fish gills to bleed slowly. This can indicate that the water quality is getting dangerous and that ammonia in the fish tank is hurting the fish’s organs.
3. Red Streaks on the Fish’s Fins
Red streaks on a fish’s body indicate fin rot, which is common in fish kept in water with high concentrations of ammonia. Keep an eye out for indications of this, such as your fish’s body seemingly bleeding. When this happens, it’s best to take action right away.
4. Fish Is Gasping for Air
Most of the time, when your fish is gasping for air at the surface of the water, it means they need more oxygen. Most of the time, this is because other pollutants like ammonia or nitrite make it hard for the gills to work properly. This strange behavior is often a sign that a fish is in trouble because it means it is trying to get more oxygen into its body than it already has.
5. Loss of Appetite
Poor water quality is the primary reason for a decrease in appetite. The temperature and acidity levels sound fine, but you failed to mention the presence of ammonia or nitrite. When these levels get too high, it can make fish so sick, which can cause them to lose their appetite and eventually die.
6. Death
Tiny amounts of ammonia have no discernible odor or color but are still extremely poisonous to fish. If you don’t know why your fish are dying, it could be because there’s ammonia buildup in the water. Too much ammonia in the water can cause illness and even death for your fish.
7. Fish is Sluggish
At first glance, fish may appear to be motionless or swimming very slowly, especially if you have a cold fish tank. But if it goes on for more than a few days, it could be a sign that there is too much ammonia in the water. High levels of ammonia in the water can make the fish slow and tired.
How To Lower Ammonia Levels In a Fish Tank
In an aquarium, you definitely don’t want ammonia anywhere near your fish. At high levels, it can hurt or kill your fish, but luckily we can stop that from happening. Here are some ways to get rid of the ammonia in your tank.
1. Water Change
When ammonia levels are high, it’s a good idea to do a water change to dilute the ammonia. When you do a water change, you replace some of the dirty water with an equal amount of clean water. This reduces the amount of unwanted chemicals in your tank.
2. Install Cycled Filters
Cycling helps your tank get the right bacteria, which eats ammonia and turns them into less harmful nitrates. By moving a cycled filter from one tank to another, you can increase the number of good bacteria in your tank and lower the amount of ammonia.
3. Water Conditioner
Water conditioner may be used to make ammonia less harmful in case of an emergency. By binding onto the ammonia, it lets your bacteria catch up and convert it into nitrates. Many aquarists say that you should always have a bottle of water conditioner on hand in the event of an emergency.
4. Use Anti-Ammonia Filter Media
One way to reduce ammonia in the water is to add media to your filter that is specifically designed to remove ammonia from your aquarium. It contains minerals that naturally remove ammonia from water without any side effects. However, it can only filter much until it’s full, and it needs to be replaced at that time.
5. Stop Feeding Fish For a While
It might seem like denying your fish food is bad for them, but it has many benefits. It can help the fish get rid of waste in their stomachs. This also reduces fish waste for a while, which can help lower the amount of ammonia in the water.
6. Do Regular Maintenance
The fish in your tank will continually produce waste products that will eventually decompose into ammonia. Ammonia levels will rise as the fish waste settles to the bottom of the tank or dissolves in the water. It is important to clean and take care of the fish tank on a regular basis so that the fish have a healthy place to live.
7. Increase Oxygenation in the Tank
Adding more air to the aquarium can help reduce the amount of ammonia in your aquarium. The ammonia gas in the water is bad for your fish and can dissolve in the water. A better flow of oxygen through the aquarium’s water will allow it to escape into the air.
How To Lower Ammonia Levels In a Fish Tank Quickly
Most of the time, it takes a day or two to slowly bring down the amount of ammonia in an aquarium. But there may be times when we really need to get as much ammonia out of the aquarium as we can. Here are six quick ways to cut down on the amount of ammonia in your aquarium.
1. Partial Water Change
Partially changing the water will reset the pH, KH, and minerals levels while lowering the levels of ammonia and phosphate. It replaces the old, ammonia-filled water with good, fresh water that dilutes the ammonia quickly in your tank. This is usually the best way that most aquarists would recommend doing this to keep your tank healthy.
2. Install Anti-Ammonia Filtration
When the level of ammonia quickly rises in the tank, this is called an ammonia spike. To do this, you’ll need an anti-ammonia filter in your tank to remove ammonia from the water directly. But these filters will only work until they have filtered out enough ammonia, after which they will stop working and need to be replaced.
3. Treat Water with Conditioners
Water conditioners are typically solutions that are added to regular tap water to make it suitable for fish. But modern water conditioners do more than just get rid of chlorine, they also get rid of ammonia. There are great water conditioner products out there that can help you quickly reduce the amount of ammonia in your tank.
4. Vacuum The Gravel
The gravel in your fish tank is an important part of it, but it could also be where ammonia is being made quickly. Fish waste and uneaten fish food can pile up in the gravel, contributing to ammonia production. When this happens, it’s best to vacuum the gravel up to stop the ammonia from getting worse.
5. Remove Decaying Plant Matter
Having a plant or leaves that are dying is bad for the quality of the water in your tank. Rotted plant matter can break down in your aquarium, which will cause ammonia to build up quickly.
6. Remove Leftover Food
As it breaks down, uneaten fish food gives off toxic ammonia and nitrite. This is especially dangerous for new aquariums that do not have enough beneficial bacteria that can quickly break down these toxins. It is always best to only feed your fish as much as they can handle.
7. Add More Beneficial Bacteria to the Tank
Pouring beneficial bacteria from a bottle directly into your tank is one way to quickly increase the number of beneficial bacteria in your tank. There are actually a lot of companies that sell live bacteria in a bottle. This can help you start a colony of good bacteria in your tank. Just check to see if the bottle has run out of time.
How To Check Ammonia Levels In Fish Tank
Use an Ammonia Test Strip Kit
It’s recommended that an ammonia test is completed once a week to ensure levels are not allowed to build up. You can also perform a test whenever you see signs of sickness in fish or lose a fish for any reason you aren’t sure of. A test strip kit provides the quickest results and is relatively easy to complete.
Use a Salicylate Ammonia Test
Another test you can perform to check ammonia levels is a salicylate ammonia test, which involves adding chemicals to a water sample to determine how much ammonia is present. These tests are thought to provide more accurate results than a test strip kit. You can repeat the test a few times to ensure ammonia levels are improving.
Use an All-Round Test Kit
Most aquarium tests are able to test for anything potentially dangerous in your tank and water, such as high nitrate levels and other harmful chemicals. Completing one of these tests can let you know whether there is too much ammonia in your water, as well as any other dangerous chemicals that could harm your fish.
Check for Smells
Ammonia has quite a particular smell, so you should be able to pick up on it. If your fish tank has developed a strange smell, test your water straight away to check for increased ammonia levels. The smell of ammonia will get stronger the higher the level in your tank is, but smaller amounts can also be detected through scent.
Check Your Filter
An indirect way to check for ammonia in your tank is to check the filter. You should be making sure to check your filter regularly to ensure it is working the way it should be to protect your tank and water from anything harmful. If it isn’t, it may be contributing to ammonia levels in the tank.
What Happens If Ammonia Levels Are Too High?
Fish Can Die
Ammonia essentially poisons your fish, causing damage to its brains and organs. The higher the level of ammonia in the water, the more difficult it is for the fish to expel it from their bodies. Eventually, this will lead to the fish dying, which can be a very painful and stressful death.
Fish Can Be Seriously Harmed
If a fish is not killed by ammonia, it can instead be left seriously injured. Ammonia can cause burns to the gills, which can lead the fish to suffer physical effects for a long time. This can be very painful for a fish to go through and can create further severe stress both physically and mentally.
Fish Can Become Very Stressed
Some fish can tolerate higher ammonia levels but can still suffer the effects. These fish may not become ill or die from high ammonia levels but may instead become extremely stressed. This can cause them to become vulnerable to developing certain diseases, experiencing color loss, or growing less.
Plants Can Suffer Too
It’s not just your fish that can suffer as a result of elevated ammonia levels – in fact; you should be keeping an eye on any plants you have in your tank too. Too much ammonia is not good for plants, and most will likely be killed by an excess of ammonia in your water. Aquarium plants absorb ammonia as fertilizer and can easily absorb too much.
Your Fish’s Behaviour May Change
An excess of ammonia in your fish tank may cause your fish to experience changes in behavior. A surface dwelling fish may begin to spend more time at the bottom of the tank, or an energetic fish may suddenly become much more listless. These changes can all happen as a result of elevated ammonia levels in the water.
How to Remove Ammonia From Fish Tank Naturally
Now that you know what ammonia is and how to identify whether or not it is too high in your fish tank let’s go over a few ways to remove ammonia from the fish tank naturally.
- Partially Change the Water in the Fish Tank
- Cycle the Fish Tank
- Increase the Air Circulation in the Fish Tank
- Improve the Filtration in the Fish Tank
- Add and Care For Live Plants in the Fish Tank
- Move to a Larger Fish Tank
- Add Beneficial Bacteria to the Fish Tank
Let’s go over each of these methods for removing ammonia from a fish tank naturally so that you can decide which works best for your fish and your lifestyle!
1. Partially Change the Water in the Fish Tank
Possibly the easiest way to lower the ammonia levels in a fish tank is to complete a partial change of the tank’s water. Replacing around thirty to fifty percent of the water in your tank can do wonders for diluting the ammonia that’s causing trouble.
To do this, take a clean bucket that has never been exposed to chemicals or soap and pour regular tap water inside. Dechlorinate this with either a dechlorinating chemical from your local pet store, or allow the water to sit overnight.
Then, simply turn off the light and filter in your aquarium and drain the correct amount with a hose before slowly pouring in the new, ammonia-free water.
2. Cycle the Fish Tank
Cycling your fish tank is the process of making sure there are living bacteria in your aquarium. If you’re new to owning an aquarium, you may not know that it actually needs some bacteria to keep a good level of control on the ammonia in your water.
Cycling a tank takes six to eight weeks and is usually performed after removing the fish from your tank. It simply means that you make sure there are plants and smaller fish like minnows and barbs in the highly-toxic water, creating good bacteria to combat ammonia levels.
After this is done, you can add your fish back into the tank, safe in an environment that will balance out the ammonia they naturally produce by breathing and digesting food!
3. Increase the Air Circulation in the Fish Tank
Increasing aeration, or the circulation of air and dissolved air through the water of your tank, is very helpful in lowering ammonia. This is because aeration allows ammonia, which is gas dissolved in water, to transfer back to the air and then out of the tank itself, where it can’t harm the fish.
To increase air circulation in the fish tank, you can either buy an air pump or a spray bar at your local pet store. Be sure that the tank is not covered with a lid when you engage in the air circulation process.
4. Improve the Filtration in the Fish Tank
If your filter isn’t working properly, ammonia levels will rise no matter what else you do to neutralize them. Therefore, make sure the filter pad is clean. The filter itself may need to be replaced or unclogged.
If this doesn’t improve things, it may be because your fish are producing ammonia faster than one filter can handle, so you need to add a second filter.
Finally, improving your tank’s filtration can involve vacuuming the bottom of your tank and getting rid of dead plants and uneaten food. These can not only produce ammonia but make it more difficult for your filter to do its job.
5. Add and Care For Live Plants in the Fish Tank
If you’re looking for a natural way to remove ammonia from your fish tank, a live plant is one of the best methods! Plants need plenty of nutrients to grow healthily and then tend to get these from the waste fish and uneaten food produce.
In this way, live plants can actually act as an ammonia-level balancer. The plants get rid of the ammonia-producing materials so that you don’t have to, and they are provided with the nutrients they need. All the while, they are also producing dissolved oxygen for your fish. Everyone wins!
Some of the most durable plants to combat high ammonia levels are java ferns and java moss.
6. Move to a Larger Fish Tank
If too many fish are in too tight a space, then there simply won’t be enough water, plants, or filtration to handle the ammonia that they produce. Consider moving your fish tank’s contents into a bigger aquarium. This will promote better dilution and give your anti-ammonia components, like filters and plants, a fighting chance to do their work.
7. Add Beneficial Bacteria to the Fish Tank
This option is best if you have a brand-new fish tank that is disturbingly high in ammonia. The reason behind this is probably that your new tank does not have the bacteria it needs to cycle through the water.
A few quick ways to add good bacteria, which will process the ammonia in the water, is by taking elements from an old aquarium and transferring them to the new one. For example, try adding gravel or even a used filter pad to the fish tank.
What Causes High Ammonia Levels In Fish Tank?
Ammonia comes from fish waste, which is something you don’t want in your fish tank. But even though you cleaned your aquarium, there may still be a lot of ammonia in the fish tank. Here are some reasons why your fish tanks might have a lot of ammonia.
1. Leftover Fish Food
It’s never a good idea to leave food in the fish tank that hasn’t been eaten. Fish food falling to the tank’s bottom will break down and make a lot of ammonia. It can also be used to supply nutrients to algae and fungi in the aquarium, which are bad for the fish.
2. Overpopulated Tank
Some fish can get too territorial if there are too many of them in a tank. This could make the fish more aggressive and cause more fights, which could kill some of them. Also, when you have too many fish in a tank, they make more waste, which also makes the ammonia level rise.
3. Use of Untreated Tap Water
Ammonia can be found in tap water that hasn’t been treated. At first, the amount may be small, but it can quickly pile to dangerous levels. If you use untreated water in your aquarium over and over again, ammonia could keep getting added to it and build up over time.
4. Sudden Changes in Water
Ammonia levels can rise in response to any quick change in the water, especially when different water types cause such changes. When you add new chemicals, like chloramine, the ammonia level can quickly rise to a dangerous level.
5. Waste Buildup
Ammonia can be produced from a wide variety of sources, including decomposing plant matter, spoiled fish food, and dead fish. Even the waste that your fish excrete can also contribute to ammonia formation. These things break down or dissolve in the water, which causes levels of ammonia to rise to dangerously high levels.
6. Insufficient Filtration
If there is too much ammonia in your aquarium, it could be because the bacteria in your aquarium is not able to break down ammonia at a faster rate as it is being made. This usually happens when your aquarium has too many fish or when your aquarium filter is broken and needs to be replaced.
7. Decaying Organic Matter
Fish or animals that die are a big source of ammonia in fish tanks. This could be a dead fish in the corner of the tank or a rotten leaf hiding behind a piece of driftwood. When this organic matter breaks down, it can release a lot of ammonia into the water.
What Does Ammonia Do in the Aquarium?
There is one circumstance during cycling your tank in which some ammonia can actually be a good thing. The typical effects of ammonia in an aquarium are useful to know when dealing with your own fish tank. Check out the list below:
- Ammonia Comes Into Contact With Bacteria
- Ammonia Turns Into a Nitrite
- Nitrites Turn Into Nitrates
- Nitrates Are Absorbed by Plants
- Water is Safe for Fish
Here is a more detailed look at the effects of ammonia in the aquarium.
1. Ammonia Comes Into Contact With Bacteria
When ammonia is first added to an aquarium (either by adding pure ammonia or letting fish food decay in a tank empty of fish), it comes into contact with bacteria. This beneficial bacteria comes from a used filter or components like old gravel at the bottom of the tank. The ammonia actually kickstarts the good bacteria, helping it to grow to a healthy level.
2. Ammonia Turns Into a Nitrite
When good bacteria come into contact with ammonia, it transforms that ammonia into nitrates or NO2. This process is what gives good bacteria their energy, and living bacteria are good for the overall environment of your fish.
3. Nitrites Turn Into Nitrates
Nitrites, or NO2, can be transformed into nitrates, otherwise known as NO3. NO3 is important because it is the kind of chemical that can actually be dissolved.
4. Nitrates Are Absorbed By Plants
When ammonia has undergone the process of being transformed into nitrates, it not only provides energy to good bacteria in the tank but can be absorbed by plants and organic life healthily. This is a big difference from ammonia’s original, toxic form!
5. Water is Safe For Fish
Once this nitrogen cycle, which started with ammonia, is complete, the water is safe for fish. When fish are added to an aquarium that has been put through the nitrogen cycle, the natural ammonia they release can be managed by the good bacteria. As long as factors like poor filtration and removal of excess waste are in place, the good bacteria will handle ammonia!
How To Prevent High Ammonia Levels In Fish Tank
There are things you can do to help reduce the amount of ammonia in your aquarium. But it’s better to be safe than sorry, especially when it comes to keeping fish. Here are some things you can do to keep your aquarium from getting too much ammonia.
1. Avoid Overfeeding
As always, you should never give your fish too much food. If your fish eat too much, it can be bad for their digestive health. Also, when the food at the bottom of the tank breaks down, it releases a lot of ammonia into the water.
2. Add Aquarium Plants
Aquatic plants do a wonderful job of controlling the amount of ammonia in your fish tank, so placing a few of them can help keep ammonia from building up too much. Plants will take in your fish’s leftover food and waste, as well as the ammonia it gives off, and turn it into fertilizer to help them grow.
3. Don’t Overstock Your Fish Tank
When you have too many fish in your tank, the amount of ammonia will naturally rise. So limiting how many fish you have in the tank at once will help keep ammonia from building up. How many fish your aquarium can hold depends on the size of the tank, but keeping the number low will help keep ammonia from building up.
4. Improve Filtration
If your filtering isn’t up to par, the amount of ammonia in your tank could go up. Among the most important things you can do to control the amount of ammonia in your water is to use a filter. To keep ammonia levels from getting too high, you could replace your filter with a better one or add another filtration system to increase the water flow.
5. Upgrade to a Bigger Tank
A bigger tank doesn’t always mean it’s healthier, but upgrading to a bigger aquarium is a great, quick way to deal with high levels of ammonia. This is because if there is more water, the levels of ammonia will be diluted quicker.
6. Avoid Using Untreated Tap Water
Tap water is usually disinfected with either chlorine or chloramine. Fish are very sensitive to chlorine, so it must be completely taken out of the water before fish can swim in it. Chloramine is made of chlorine and ammonia, which can also lead to high levels of ammonia in the tank.
7. Do Regular Maintenance
Since an aquarium is a closed environment, it needs to be cleaned often so that harmful substances don’t build up and hurt the fish that live in it. Over time, algae and waste from living things will build up in your fish tank, as well as ammonia or nitrates. Cleaning and taking care of your fish tank on a regular basis is a great way to keep it a safe and healthy place for your fish to live.
FAQ
How Long Does It Take to Lower Ammonia Levels in Fish Tank?
The amount of time it takes to get rid of the ammonia in your tank depends on what caused the problem in the first place. Though, in normal situations, the ammonia levels can be brought down to safe levels in a matter of days.
Recap
It is very important for us aquarists to keep the aquarium safe so that the fish can live there happily. One way to keep the aquarium safe is to keep the levels of ammonia and nitrates low to keep your fish from getting sick. If the ammonia level in the water is too high, there are simple things we can do to lower it, like treating the water or putting in an air pump to add more oxygen to the water. There are also easy and simple things we can do to stop ammonia levels from getting out of hand in the first place. These include things like putting plants in your aquarium, making it bigger, and not putting too many fish in it. We can keep our fish happy and healthy by doing these simple and easy things.
