How to Treat Ammonia Burns in Fish

Butterfly fish

Ammonia burns are no laughing matter; they may swiftly endanger your aquatic critters' lives and damage the tank ecosystem. If you keep fish, you should be aware of the symptoms of ammonia burns, where the excess comes from, and how to treat your fish.


Ammonia is a waste product of a fish's protein metabolism that is discharged directly into the water through their gills. The skin, eyes, fins, and gills of fish are chemically "burned" when levels in fresh or saltwater reach lethal levels. Low amounts of in the water can create an increase in mucus on the skin, making the fish's skin seem pale, and film the gills, making it difficult for the fish to breathe through the gills. External and/or internal can result from burns. Ammonia levels that are too high can be fatal.

Signs of Ammonia Burns

The effects of ammonia burn usually do not appear until two or three days after being exposed, although rapid increases in ammonia can cause sudden death in the fish. Signs to look for are:

  • Ragged or frayed fins
  • Cloudy eyes
  • Rapid gilling
  • Lack of appetite
  • Red blotches or streaks


"New tank syndrome" can result in ammonia burns. The build-up of ammonia to a dangerous level during tank cycling in a new aquarium might happen quicker than the helpful bacteria that break down fish wastes can proliferate. The nitrogen cycling process begins with this phase. In new aquariums, it's critical to test the aquarium water for ammonia on a regular basis.

If preventative measures are not followed during transportation, whether ordering fish from an internet provider or your local fish store, dangerous levels of ammonia in the bag transporting water can be reached in a very short amount of time. This also applies to the water in a transport container while packaging and transporting fish.

After arriving at your destination, the animals in the bags or transport containers must be acclimated before being placed in their new habitat during acclimatization processes. The longer they stay in the water throughout the procedure, regardless of the method you choose, the more ammonia will build up.

There are no helpful biological bacteria present when fish are confined to a container for the treatment of a sickness or illness, allowing ammonia to build up. This is especially true when treating animals in quarantine tanks, as many drugs also kill beneficial microorganisms.

Excess bioload overwhelms the biological filter's capacity to compensate if too many fish and/or other animals are added too rapidly to even a well-seasoned or cycled tank.


The first step is to make a water change to reduce the ammonia levels in the aquarium. To check that the ammonia has been eliminated, test the water using an ammonia test kit or test strip.

  • Isolate the fish in a quarantine tank, and follow proper QT protocol.
  • Treat the fish in the QT with a quality antibiotic or antibacterial medication.
  • It is best not to treat fish in the main aquarium with antibiotics. These medications can greatly weaken and even completely kill off the biological filter bacteria, which in turn will cause new tank syndrome to occur, or result in the aquarium having to cycle all over again.

In three to five days, signs of successful therapy should appear. Treatment should be maintained until the fish begins to feed normally, after which it can be reintroduced to the main tank.


If allowed to collect in the water, ammonia is the principal nitrogenous waste product of fish and is extremely hazardous to them. A good biological filter (biofilter) will break down the ammonia that the fish create, keeping the fish safe. Maintaining high water quality also necessitates frequent water changes. While the beneficial bacteria in the biofilter establish themselves in new aquariums, 10% or more of the water should be withdrawn and replaced with dechlorinated water once a week. A 25% water change every two to four weeks is recommended for aquariums with established biofilters. Measure the ammonia in the aquarium water with a test kit to verify it is at a safe level (preferably zero).

Commercial ammonia-binding treatments are also available in pet and fish stores, making the water non-toxic to the fish. These are useful while setting up a new aquarium, during the cycle phase, and when adding new fish to the aquarium (which raises the bioload), as well as after cleaning the tank or filter (which can decrease the bacterial population in the biofilter). If ammonia is identified in the aquarium water, test it using test strips or kits, and then apply the ammonia neutralizing solution according to the manufacturer's dosage instructions.


Another source of ammonia burns is chloramine-containing tap water, which releases ammonia into the aquarium when the water is changed. If your tap water includes chloramine, use a dechlorinator to remove the chlorine and an ammonia neutralizer to remove the ammonia.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.