Axolotls (Ambystoma mexicanum) are salamanders endemic to the Lake complex of Xochimilco outside of Mexico City. They are most recognizable by their retained gills and tad-pole like body as this species does not undergo natural metamorphosis like other salamanders. In captivity, they typically live between 10-15 years old. On average their size ranges from 9-10 inches long and females are larger than males. Sexual maturity occurs at 10 months for males and 12-18 months for females. To determine gender you have to look at them from the side. Males have a cloacal bulge (bulge behind their back legs) and females do not. Males will also have black nails, but this attribute may not be as reliable in some color morphs. There are a variety of color morphs in the pet trade. Commonly you will see the wild type (mottled black/ brown), albino, and leucistic. They are very common in the pet trade and in research laboratories and have become critically endangered in the wild due to pollution and introduction of invasive species. In their natural environment, they are bottom dwellers so keep that in mind when designing their aquarium.
Aquarium Set Up
A proper aquarium set up is critical to keeping your axolotl healthy. The typical recommendation is a 10 gallon aquarium for juvenile axolotls and 20 gallons for adults. Here at Arizona Exotic Animal Hospital we recommend a minimum of 30-40 gallons being your minimum tank size for your adult axolotl. We also recommend a longer tank rather than a deeper tank so your axolotl has more room to exercise and explore and because larger tanks allow for higher volume of water making it easier to maintain good water quality. Your aquarium set up should include an external canister filter that can be attached to a spray bar inside the aquarium to disperse the water to maintain a slow, even water flow. The water temperature should be maintained between 60-65 degrees Fahrenheit. This will require having an aquarium chiller as part of your set up. You need to purchase an appropriately sized chiller for the size of your aquarium. Again, an external chiller is recommended to reduce temperature pocketing and maintain a more ubiquitous water temperature. The preferred pH is 7.4- 7.6 but pH between 6.5-8.0 is acceptable. Consistency is key when it comes to pH. If your axolotl has grown up slightly out of those parameters and is healthy we do not recommend using pH up or down products to get within the ideal range. Those products can cause large swings in pH which can be very harmful to your axolotl. You may also consider making your own aquarium water by remineralizing reverse osmosis water if your source water is too far out range. If you are using tap water, you must use a water dechlorinator. Ensure the product you use is able to remove chlorine and chloramine. Other major water parameters to monitor are Ammonia and Nitrite which should be 0 ppm and Nitrate which should be less than 5-10 ppm. Our preferred testing kit is the API Freshwater Master Kit. Please research other sources about cycling a new tank, water quality testing, and the nitrogen cycle for more information on water quality.
Since Axolotls may try to swallow items that can fit in their mouth we recommend using aquarium sand or larger stones for your substrate and avoiding gravel or small pebbles.
Axolotls have very delicate skin and gills so avoid placing any structures in the aquarium that have sharp edges. One tip is to run your finger around any edges or sides of silk plants and if it is not smooth or scratches you then avoid use. Axolotls prefer to have structures where they can hide and rest and helps reduce their stress and mimics their natural behavior. You can use live plants in their aquarium but some can carry parasites and diseases that may harm your axolotl. Strict quarantine and biosecurity measures should be taken prior to introducing any live plants or another axolotl to your aquarium.
Axolotls do not require specific lighting so soft display lighting can be used. Being bottom dwellers they are adapted for low light conditions and thus, do not have good vision. They have adapted strong olfactory senses to compensate. Specific lighting may be needed for live plants.
Axolotls are carnivores. In the wild they typically eat mollusks, worms, insect larvae, crustaceans and sometimes small fish. In captivity, we do our best to mimic those conditions to ensure they are receiving the proper macro and micro nutrients to prevent metabolic disease. Larvae should be fed brine shrimp until they are about 1 inch long and then transitioned to California blackworms. Adult axolotls should be transitioned to a pellet diet. There are multiple axolotl pellet diets on the market and one of the most common diets is Rangen Salmon Pellets (soft moist sinking pellets 3/16”). Bloodworms, blackworms, tubifex worms, and pieces of earthworms can also be given to vary the diet and provide enrichment along with the pellet diet. Freeze dried products provide little nutritional value overall. Live products are not recommended if they do not come from a reliable pathogen/ parasite free source. Adult axolotls should be fed 2-3 times a week and any uneaten food should be removed promptly to maintain good water quality. Axolotls are prone to obesity due to their slow metabolism and low energy demand so avoid overfeeding.
Poor water quality and inadequate husbandry can lead to a variety of problems like inappetence, buoyancy issues, bacterial and fungal infections, and eye and gill disease. Trauma can occur if axolotls are housed with fish or other axolotls. Males should not be housed together unless there are enough areas for them to hide. If you are concerned your axolotl is sick, please call us or another veterinarian in your area. Most over the counter remedies cause more harm than good and you should never give your axolotl a medication without direction by a veterinarian. Some medications cause harm to the microbiota in your filter that helps keep your entire aquarium healthy. Your axolotl’s aquarium is an ecosystem and when treating your sick pet we have to consider the health of your entire aquarium.