Aquarium Ammonia Spikes 101

Aquarium Ammonia Spikes 101 main image Aquarium Ammonia Spikes 101 image

What causes ammonia spikes?

Ammonia spikes can be a common problem in your aquatic journey and can be frustrating to deal with. This article however will help cover the essential information you need to know to ensure you have a happy and healthy aquarium for your favourite fish. This will include causes of ammonia spikes, signs and symptoms, treatment and prevention.


There are many things that can cause a spike in ammonia, however the most common is known as New Tank Syndrome. New tank syndrome is caused by the lack of beneficial bacteria in the water. In a well-established tank beneficial bacteria is already present and will keep the water at the appropriate levels as it is able to break down the ammonia and nitrite into harmless nitrogen compounds. In a new tank the beneficial bacteria have not had time to grow and establish themselves, without the beneficial bacteria the ammonia and nitrite levels will rapidly rise and quickly become toxic to your fish. If a new tank is not your problem, ammonia spikes can be caused by the following;

  • Overstocking of fish
  • A too thorough tank clean
  • Overfeeding of fish causing excess food and fish by-products
  • Sudden changes in temperature of water
  • Changing old gravel to new gravel
  • The filtration bacteria can’t handle the amount of ammonia
  • High rates of organic decomposition


What does an ammonia spike look like?

Spikes in ammonia leading to ammonia poisoning can occur suddenly or over a matter of days. Therefore, it is important to conduct regular testing and monitoring of your fish. Generally, symptoms are subtle to begin with, however can rapidly change. Some signs and symptoms to look out for include;

  • Lethargy and weakness
  • Laying on the bottom of the tank
  • Loss of appetite
  • Inflamed or bleeding gills
  • Gasping for air at the surface of the tank
  • Jagged and torn fins
  • Redness and inflammation on fins
  • Inflammation to eyes and anus


Treatment for ammonia spikes

Its important to test your water on a regular basis to keep an eye out for ammonia spikes. We highly recommend the API Master Test Kit which comes with everything you will need to effectively test your water. Ammonia levels above 0 ppm indicate an ammonia spike, and this requires treatment ASAP.

Treatment strategies include the following;

  1. Immediately do a 30-75% water change (the Amount changed will depend on the severity of the ammonia spike)
  2. Cycle your tank – this can be a timely process, Seachem Stability is an easy way to speed up the process
  3. Remove any dead or rotting vegetation
  4. Look for and remove dead fish
  5. Remove uneaten food
  6. Vacuum gravel
  7. Use a water conditioner such as Seachem Prime to stabilise your tank while figuring out source of ammonia spike
  8. Make sure all filters are working, no clogging and that water is flowing freely
  9. Reduce amount of food when feeding
  10. Put ammonia removing pellets into your filter
  11. Reduce number of fish in tank if overstocked



Prevention is key in aquarium caretaking and here are some handy tips to make sure you stay on top of caring for your tank.

  1. Use the Seachem Ammonia Alert if you don’t have time for regular water testing
  2. Avoid overstocking fish and overfeeding
  3. Have the right filtration system for your tank, you may need an external canister filter with a hang on filter
  4. Use live plants in your tank
  5. Add beneficial bacteria as required
  6. Perform regular water changes




subscribe to our newsletter