Axolotls are amphibians that spend their entire lives in an aquatic, larval state, a phenomenon known as neoteny. They retain external gills and a tail fin as adults, unlike most other salamanders that undergo metamorphosis to a terrestrial form.
Typical Adult Size
Adult axolotls typically reach an average length of 20 to 30 centimeters (8 to 12 inches) from nose to tail tip. While this range represents the common size observed in captivity, some individuals can grow larger. Exceptional cases have seen axolotls reach lengths of up to 38 centimeters (15 inches), and in rare instances, even 45 centimeters (18 inches).
Key Factors Influencing Growth
An axolotl’s growth is influenced by several environmental and biological factors. Providing optimal conditions is important for their development.
Diet plays a significant role in an axolotl’s growth. As carnivores, axolotls require a protein-rich diet. Consistent feeding with high-quality foods, such as earthworms, blackworms, bloodworms, and specialized axolotl pellets, supports healthy development. Conversely, underfeeding or an inadequate diet can lead to stunted growth.
Water quality and temperature are important for an axolotl’s well-being and growth. Axolotls are sensitive to their aquatic environment, requiring pristine water conditions with ammonia and nitrite levels at zero parts per million (ppm) and nitrates below 20 ppm. Maintaining a water temperature between 16 and 18 degrees Celsius (60-64 degrees Fahrenheit) is ideal, as temperatures outside this range can cause stress and hinder growth.
Genetics also influence an axolotl’s ultimate size. Some individuals are predisposed to grow larger based on their lineage, while genetic conditions can result in smaller sizes, such as “minis” or “dwarfs.” The size of the tank and the space available to the axolotl can also impact their growth. Ample space allows for proper movement and reduces stress, which can otherwise inhibit growth.
Growth Stages and Rate
Axolotls undergo distinct growth stages from hatching to maturity. They hatch from eggs after 10 to 14 days.
Newly hatched larvae measure around 0.5 inches (1.3 cm) and begin eating within hours. They experience rapid growth during their juvenile phase, typically gaining about 1 inch (2.5 cm) in length per month for the first six to eight months. This rapid development necessitates consistent feeding and a suitable environment.
Axolotls generally reach sexual maturity between six months and one year of age. Reaching their full adult size takes longer, typically occurring between 18 and 24 months. Growth slows considerably after this period, though some individuals may continue to grow at a much slower rate for a few more years.
Practical Considerations for Owners
Understanding an axolotl’s potential size has practical implications for their care. Providing adequate space and appropriate feeding are important for their health and development.
For a single adult axolotl, a minimum tank size of 20 gallons (approximately 75 liters) is suggested, with a 20-gallon long tank offering more beneficial floor space. Many owners prefer a larger tank, such as 29 or 40 gallons, to provide more room for exploration and to help maintain stable water parameters. Because axolotls are bottom-dwellers, prioritizing tank length and width over height is generally recommended.
Proper feeding schedules are tailored to an axolotl’s age to support healthy growth without overfeeding. Hatchlings and very young juveniles (0-3 months) benefit from being fed two to three times daily due to their rapid growth and high energy demands. As they progress to the juvenile stage (3-12 months), feeding can be reduced to one to two times per day. Adult axolotls, typically one year and older, have a slower metabolism and generally only require feeding every other day, or two to three times per week. Removing any uneaten food promptly helps maintain water quality, which is important for their overall health.