Some of the most common mistakes with axolotl care are related to water quality. Good water quality and a properly cycled tank are essential to keeping your axolotl healthy. Cycling a tank can take as long as 6-8 weeks, so do not get discouraged. Let's break down the Nitrogen Cycle so we can better understand what it is we are trying to accomplish.

Axolotls secrete nitrogenous waste products in the form of ammonia. Uneaten food and other wastes produce ammonia as they decompose as well. In a healthy established aquarium, bacteria then feeds upon the ammonia and turns it into what we call nitrites (nitrous acid). A secondary group of bacteria then converts the nitrites to nitrates (nitric acid). Ammonia and nitrites are toxic to axolotls, and this is where most problems with new aquariums occur. Cycling refers to the establishment of an active beneficial bacteria culture, otherwise referred to as a biological filter, or biofilter. This bacteria breaks down axolotl wastes. In a brand new un-cycled aquarium, the levels of ammonia and nitrite will rise, sometimes reaching lethal levels of toxicity. Once the bacterial populations are established, they break down these compounds into less toxic forms. At this point, the aquarium would be considered a cycled, or established tank.

Ideal Test Results
(during cycling period)

  • pH: 6.8 - 8.0

  • ammonia: < 1.0 ppm

  • nitrite: < .5 ppm

  • nitrate: 0 - 10 ppm


Ideal Test Results
(for an established tank)

  • pH: 6.8 - 8.0 (& steady)

  • ammonia: 0 ppm

  • nitrite: 0 ppm

  • nitrate: < 40 ppm


There are several methods to cycling an aquarium, cycling with animals or fish-less (amphibian-less) cycling.

Cycling with Animals

The majority of established aquariums were cycled with fish or other aquatic organisms. While this is an effective way to cycle a tank, it can be lethal to the animals unless done properly.

When cycling with animals, it is important to feed your axolotl as little as possible (while maintaining proper nutrition), and remove uneaten food and other waste as quickly as possible. Testing the water daily for ammonia is critical at this stage. If dangerous levels are found, large water changes (sometimes daily) will be needed to avoid sickness or death. A freshwater test kit, such as the API Freshwater Master Kit, will be an essential tool during the cycling process.

Cycling Without Animals (Amphibian-less Cycling)

As an alternative, your aquarium can be cycled without any animals present. For this process, you will need not only your test kits for ammonia, pH, nitrite and nitrate, but also a source of ammonia. Possible sources for the ammonia are easily decomposed materials such as frozen brine shrimp, or even household scent-free ammonia.

First, set up your aquarium using de-chlorinated water and let it run for 24 to 48 hours. This will allow you time to make sure all of your equipment is running properly. Test the water for all of the above listed parameters. These will be your starting base-line measurements. After the aquarium has been running for the recommended time period, add a small amount of your ammonia source.  After 24 hours, test the water and record new results. Test the water every day or two and monitor the changes. When the ammonia level begins to drop and the nitrite levels begin to rise, add another small amount of ammonia to keep feeding the bacteria. Keep testing the water quality, and when the nitrates begin to rise, dose the tank with the ammonia source again. This should be the last dose required to finish the cycling process.

At this point, you should see a small rise in the ammonia level, a small rise in the nitrite level and a continuation in the rise of the nitrate level. When the ammonia reading drops to zero, the nitrite drops to zero and the nitrate is at a measurable level, the aquarium is considered to be cycled. Before you add any animals to the aquarium, do a 20% water change to lower the level of the nitrates. Different animals tolerate nitrates at different levels, but a safe rule of thumb is to keep your nitrate level below 60ppm. Typically, a 20 to 30% water change each week is enough to keep levels in a safe range.

It is important to note that while the tank is now cycled, the bacterial population will need to grow and compensate for your axolotl being added to the aquarium. The water should be tested on at least once per week to monitor water quality and hopefully prevent potential ammonia and nitrite poisoning.

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