The Axolotl: 2026 Guide to Biology, Husbandry, and Genomic Genetics

The Axolotl (Ambystoma mexicanum) is a caudate amphibian endemic to the Xochimilco canal system in Mexico. This species is distinguished by neoteny—a biological condition allowing it to retain external gills and larval features throughout its life—coupled with an extraordinary capacity to regenerate complex organs and limbs.

Beyond being a “smiling-faced” salamander, the axolotl is a biological treasure, a cultural icon, and a prominent figure in the aquarium hobby. Originating exclusively from Mexico City’s lacustrine complex, this amphibian captivates both scientists and nature enthusiasts alike.

Named axolotl or “water monster” by the ancient Mexica, it was intrinsically linked to the deity Xólotl, brother of Quetzalcóatl (Aguilar & Luría, 2016). According to legend, the god transformed into this creature to evade sacrifice, solidifying its role as a pillar of Mexican identity.

Currently, it serves as a fundamental biological model in tissue therapy research due to its ability to reconstruct various organs at any stage of its life cycle (Antonio et al., 2021); furthermore, it is key to studies in development, electrophysiology, and regeneration (Randal et al., 2009). Nevertheless, this evolutionary gem faces a severe crisis: the axolotl is critically endangered in its natural habitat due to urbanization, water pollution, and the introduction of invasive species.

In this article, we will comprehensively explore Ambystoma mexicanum: from its fascinating biology and conservation efforts to a detailed guide for its responsible husbandry in captivity.

Key Points: Everything You Must Know About the Axolotl

• Biological Enigma (Neoteny): Unlike other amphibians, the axolotl (Ambystoma mexicanum) reaches sexual maturity while retaining its larval traits, such as its feathery gills, remaining in a state of “eternal youth” throughout its entire life.
• Giant Genome: Its genetic map is 10 times larger than the human genome ($32\text{ Gb}$), representing a goldmine for regenerative medicine and evolutionary studies.
• Critically Endangered Status: It is critically endangered in its natural habitat (Xochimilco) due to pollution, urbanization, and invasive species, though UNAM’s “chinampero refuges” offer a glimmer of hope for recovery.
• High-Specialty Husbandry: This is not a pet for beginners. It requires constant cold water (ideally $18\text{°C}$), aquariums of at least 40–50 liters per individual, and rigorous management of ammonia and nitrites to prevent diseases such as hydrocoeloma.
• Carnivorous Diet: They are strict carnivores in their adult stage. Their diet must be protein-rich ($45\%$) and can be optimized through operant conditioning for the use of specialized pellets.

What is an Axolotl? The “God of the Waters” of Xochimilco

The axolotl is a salamander that defies the conventional rules of biology. Unlike other amphibians, this organism possesses a unique genetic structure and does not naturally undergo full metamorphosis, making it an essential model for the study of evolution and regenerative medicine. Also known as axolotes, these amphibians are distinguished by maintaining their larval traits throughout their lives and by their strictly aquatic nature. While most salamanders undergo physical changes to migrate to land, the axolotl is celebrated for its neoteny.

Neoteny: The Secret of “Eternal Youth”

This biological phenomenon implies that the axolotl permanently retains its larval characteristics (González & Jardón, 2024). This includes its iconic external feathery gills, fundamental for underwater respiration, and its dorsal fin. Despite maintaining this juvenile appearance, the specimen reaches sexual maturity and can successfully reproduce in this state.

Taxonomic Classification

According to Ávila et al. (2021), Mexico is home to 18 of the 33 species of salamanders in the genus Ambystoma, distributed from southern Canada to central Mexico; nevertheless, most are classified within high-risk categories. In this analysis, we will focus exclusively on the emblematic Xochimilco axolotl.

• Kingdom: Animalia
• Phylum: Chordata
• Class: Amphibia
• Order: Caudata
• Family: Ambystomatidae
• Genus: Ambystoma
• Species: Ambystoma mexicanum
• Common Names: Mexican axolotl, pink salamander, or “water monster.”

Connection to Salamanders

Although popularly called the “Mexican walking fish,” it is important to specify that it is not a fish, but an amphibian closely related to the tiger salamander. In exceptional cases—generally induced by hormonal changes in laboratory settings—an axolotl can undergo induced metamorphosis, transforming into a terrestrial form that develops functional lungs and loses its external gills.

Is it possible for an axolotl to transform into a terrestrial salamander?

The answer is yes, although it is an extremely rare and biologically stressful phenomenon. Under natural conditions, the axolotl remains in its aquatic state; however, in controlled laboratory environments, metamorphosis has been successfully induced through the artificial administration of iodine or thyroxine.

During this process, the specimen undergoes drastic anatomical changes: it loses its iconic external gills and develops functional lungs, acquiring a morphological appearance similar to that of the tiger salamander (Ambystoma tigrinum). Nevertheless, this transition carries a severe biological cost, as its life expectancy is usually drastically reduced following metamorphosis, underscoring the exceptional and delicate nature of its neotenic biology.

External Anatomy and Morphology of the Axolotl

Physically, the axolotl retains the appearance of a “giant tadpole.” Its most distinctive feature is the three pairs of external gills, which have a feathery appearance and emerge from the sides of its neck, allowing it to filter oxygen directly from the water.

Regarding its physiognomy, Mexican salamanders possess limbs with four toes on the forelimbs and five on the hindlimbs. Although they can reach a maximum length of 30 cm, the average size oscillates around 15 cm, with a weight ranging between 125 and 180 grams. Their skin is smooth, extremely permeable, and covered by a protective mucosal layer. For a more in-depth technical analysis of their internal structure, consulting the study by Ramírez-Macal et al. (2022) is recommended.

Key Physical Attributes

• Respiratory System: Lateral feathery gills for aquatic oxygenation.
• Skeletal Structure: A partially cartilaginous skeleton that facilitates its regenerative capacity.
• Sensory Capability: They possess limited vision, compensated by high sensitivity to vibrations and chemical signals in their environment.

Color Varieties and Morphs

In its natural habitat, the axolotl typically presents mottled black or brown tones. Nevertheless, selective breeding in captivity has given rise to various chromatic variants known as “morphs.” The most common and valued classifications are detailed below:

In addition to these, there are varieties such as the White Albino (red eyes), the Axanthic, and specimens with dark spots on a pale background, the result of complex evolutionary genetics and responsible breeding.

The Axolotl Genome: A Giant 10 Times Larger than the Human Genome

The decoding of the Ambystoma mexicanum genetic code represents one of the most ambitious milestones in modern biology. Nowoshilow et al. (2018) successfully sequenced and assembled its genome, revealing an expanse of 32 gigabase pairs (Gb), a figure ten times the size of the human genome. This study identified transcripts and genes exclusive to non-amniote vertebrates, which are considered fundamental pieces of its extraordinary regenerative capacity.

Furthermore, research by Smith et al. (2019) overcame a historic technical barrier by organizing this immense genetic material into 14 chromosomes. The resulting assembly covers 27.3 Gb and integrates 94% of the annotated gene models. This breakthrough increased genome contiguity by more than 800-fold, allowing molecular scaffolds to grow from an average of 3 Mb to a robust 2.46 Gb, thereby facilitating the precise mapping of its biological functions.

Regeneration: The “Holy Grail” of Modern Medicine

The most fascinating characteristic of the axolotl is, undoubtedly, its scar-free regenerative capacity. While the human biological system responds to severe injuries through the formation of scar tissue (fibrosis), the axolotl deploys a unique response mechanism: upon the loss of a limb or damage to an organ, the amphibian generates a blastema. This mass of pluripotent stem cells has the power to reconstruct the lost structure identically and functionally.

A Model of Complete Regeneration

The Mexican axolotl stands out as one of the few tetrapod species capable of regenerating entire skeletal elements in adult limbs (McCusker et al., 2016). Its astounding restorative power also extends to the tail and gills (Makanae et al., 2020). According to Sámano et al. (2021), this biological process integrates the perfect regeneration of:

• Nervous tissue.
• Bone structure.
• Blood vessels.

This entire complex assembly occurs within an astonishingly short period of less than 40 days.

The Preeminent Model Organism

These extraordinary faculties have established Ambystoma mexicanum as the preferred model organism in laboratories worldwide. Its study is fundamental to the future of regenerative medicine, offering critical keys for the treatment of complex injuries, organ recovery, and the advancement of biotechnology applied to human health.

The Natural Habitat of the Axolotl: An Ecosystem in Crisis

The axolotl predominantly inhabits cold, oxygenated bodies of water with abundant submerged vegetation. Historically, this amphibian was distributed across the lacustrine systems of the Valley of Mexico; currently, its presence is critically concentrated in the canals of Lake Xochimilco and the remnants of Lake Chalco, with reported sightings also documented in the Chapultepec area (González & Jardón, 2024).

The aquatic environment of these zones is traditionally characterized as alkaline and slightly brackish. Nevertheless, the degradation of water quality—a byproduct of urbanization and human activity—now represents the greatest challenge to its survival. The preservation of this ecosystem is not only vital for Ambystoma mexicanum but is also fundamental for maintaining the balance of biodiversity in the central region of Mexico.

The Axolotl in Critical Danger: A Fight Against Extinction

The Mexican axolotl (Ambystoma mexicanum) is classified as “Critically Endangered” according to the IUCN Red List (2019). This alarming situation is the direct result of urban pollution in Mexico City, habitat fragmentation, and the introduction of competitive exotic species in the Xochimilco canals (Webb, 2023). Added to these factors is its historical consumption; for centuries, the axolotl was a staple ingredient in local gastronomy, featured in dishes such as tamales (tlapiques), soups, and moles (Astorga et al., 2025).

Vulnerability extends across the entire genus: SEMARNAT (2018) notes that of the 16 endemic axolotl species in Mexico, 15 are protected under NOM-059-SEMARNAT-2010 within various risk categories. Although the “Action Program for the Conservation of Ambystoma spp.” has made significant strides, the species has yet to surpass the threat threshold. Recently, a new environmental concern has been identified: microplastics, which severely impact larval feeding processes (Manríquez-Guzmán et al., 2023).

Conservation Strategies and Efforts

In light of this outlook, various institutions are leading initiatives to rescue the species from total disappearance:

• Chinampero Refuges: Through a strategic collaboration between UNAM and local farmers, isolated and filtered canals have been created. These refuges recreate the historical ecosystem, keeping out invasive species and ensuring optimal water quality. In this regard, Fernández et al. (2025) highlight that 42 km of canals remain suitable for restoration as refuges, which would help mitigate the effects of land-use change.
• Captive Breeding and Reintroduction: Specialized programs maintain genetically diverse populations. However, returning to the wild presents behavioral challenges; captive-bred specimens often lack evasion instincts against predators such as herons.
• Adaptation and Foraging Success: Despite these challenges, studies by Ramos et al. (2025) demonstrate that hatchery-reared axolotls are capable of surviving and successfully foraging in both restored areas of Xochimilco and controlled artificial wetlands, such as La Cantera Oriente (LCO).

Axolotl Nutrition and Feeding: From Habitat to Aquarium

Given their unique characteristics, it is common to wonder: what exactly does an axolotl eat? In their natural environment, their diet is diverse; according to Zambrano et al. (2010), they consume everything from organic matter and algae to small crustaceans (amphipods and isopods), insects, snails, and small fish. Nevertheless, specialists such as Mena and Servín (2014) emphasize that adult specimens are, in essence, strict carnivores.

Diet According to Developmental Stage

• Larvae: They feed primarily on micro-crustaceans such as cladocerans (Moina macrocopa), ostracods, and rotifers.
• Juveniles and Adults: Although specialized commercial foods exist, they can be nourished with trout feed supplemented with mosquito larvae, Artemia, water fleas (Daphnia), Tubifex, earthworms, and guppy fry.

Optimization of Commercial Diets

If a specimen shows resistance to balanced feed, scientific literature offers effective solutions:

• Attractants: Ocaranza et al. (2021) suggest using chicken oil to incentivize consumption in juveniles, while Montoya-Martínez et al. (2022) recommend the inclusion of fish or shrimp meal.
• Conditioning: A recent study by Servín et al. (2025b) demonstrated that it is possible to train axolotls through operant conditioning (using stainless steel forceps) to accept high-protein pellets, maintaining their health and fostering natural predatory behaviors.

Nutritional Requirements and Protocol

For optimal development, Manjarrez-Alcívar et al. (2022, 2024) recommend artificial diets with 45% protein and up to 8% lipids. Regarding frequency, the protocol established by Mena and Servín (2014) is as follows:

Professional Tip: It is recommended to train axolotls to feed always in the same sector of the aquarium; this facilitates monitoring their intake and helps maintain water cleanliness.

Axolotl Reproduction: Maturity in “Eternal Youth”

As a strictly neotenic species, the axolotl possesses the extraordinary capacity to reach sexual maturity while retaining its larval traits, without the need to undergo metamorphosis into a terrestrial life form. In its natural habitat, the reproductive cycle reaches its peak during the month of February. To optimize reproductive success in controlled environments, Figiel (2023) suggests sex-differentiated thermal management: it is recommended to maintain females at a temperature of $23\text{°C}$ and males at $19\text{°C}$, a strategy that allows for the maximization of gonadosomatic indices and ensures a healthy spawn.

Maturity and Sexual Dimorphism

These Mexican salamanders reach reproductive fullness at approximately one year of age. At this stage, morphological differences between the sexes become evident:

• Males: They typically present a more elongated body and a notably swollen cloaca.
• Females: They tend to be more robust and rounded, especially during egg production.

A revolutionary finding by Haluza et al. (2026) reveals that axolotls experience extremely limited reproductive senescence. This means that, unlike other vertebrates, they maintain functional fertility exceptionally well into very advanced stages of their lives—a fact that reinforces their status as a model organism in studies of longevity and cellular vitality.

Sex identification in Ambystoma mexicanum is primarily based on the observation of the cloacal region. In males, there is a notable increase in the size of the cloacal glands, perceptible to the naked eye (Mena & Servín, 2014). This morphological difference is due to a characteristic pericloacal hyperplasia in the male, which contrasts with the more discreet anatomy of the female (Ramírez et al., 2022).

Furthermore, the reproductive biology of females is highlighted by an astounding longevity. Research by Haluza et al. (2026) reveals that they possess an exceptional biological capacity to protect their ovarian reserve over the long term. This mechanism allows them to preserve the vast majority of their oocytes in early stages of development, even reaching 7 years of age, maintaining a reproductive viability that is unusual for their taxonomic group.

The Courtship Ritual and Fertilization in the Axolotl

Ambystoma mexicanum exhibits an oviparous internal sexual reproduction system. The process begins with a courtship ritual where the male guides and gently nudges the female. Subsequently, the male deposits small, conical gelatinous masses called spermatophores onto the substrate, which contain the spermatozoa. After selecting one of these packets, the female picks it up with her cloaca to achieve internal fertilization of her eggs. Following the mating ritual, females deposit between 100 and 600 eggs per clutch onto various surfaces, showing a clear preference for aquatic vegetation.

Embryonic Development: From Fertilization to Hatching

The formation process of the Mexican axolotl has recently been detailed with unprecedented precision. García-González et al. (2025) described a total of 49 morphological stages, from zygote formation to larval hatching. This scientific update expands upon previous classifications by identifying critical early phases (stages 5 to 12), successfully distinguishing the progressive reduction of blastomeres (individual cells) during cleavage.

Documented Developmental Phases

According to the study, the 49 stages are grouped into five fundamental biological phases:

1. Fertilized Oocyte: Commencement of the cycle following fecundation.
2. Cleavage (Segmentation): Active cell division and blastomere organization.
3. Gastrulation: Formation of the germ layers.
4. Neurulation: Early nervous system development.
5. Organogenesis: Formation and refinement of vital organs.

Hatching Times and Thermal Factors

Research by García-González et al. (2025) determined that, under a constant temperature of $16\text{°C}$, the period from fertilization to hatching is approximately 350 hours (with a variable range of 312 to 388 hours). This data is crucial for laboratory and hatchery management, as it establishes a temporal standard for monitoring reproductive success. According to investigations by Servín et al. (2025a), this period encompasses roughly 14 to 15 days under these controlled conditions.

Post-Hatching Stage and Survival

Once Ambystoma mexicanum larvae emerge from the egg, their metabolism activates rapidly, and they begin feeding just one day after hatching. In this critical phase, it is essential to implement management strategies in the rearing aquarium:

• Refuges and Hiding Places: The inclusion of dense vegetation or small structures is mandatory to mitigate cannibalism, a natural but controllable behavior at this stage.
• Early Feeding: Live microorganisms (such as rotifers or Artemia) must be provided to ensure vigorous growth.

Cryopreservation and Biobanks: The Genetic Future of the Axolotl

Gamete management has evolved drastically, becoming a cornerstone of ex situ conservation. According to Figiel (2020), it is feasible to store spermatophores at controlled temperatures ($0$, $3$, and $6\text{°C}$) for up to 28 days. Additionally, Rivera et al. (2021) have standardized cryopreservation protocols that facilitate international genetic exchange without the risks associated with transporting live specimens.

Advances in Germplasm Repositories

The urgency to preserve genetic diversity has driven the development of highly efficient germplasm repositories. A fundamental study by Coxe et al. (2024) established an optimized collection method via “stripping” (abdominal massage), successfully obtaining between $25$ and $800\text{ µL}$ of spermatic fluid with concentrations of up to $8.9 \times 10^7$ spermatozoa/mL. To ensure post-thaw viability, researchers determined that:

• Cryoprotectants: A combination of $5\%$ DMFA (dimethylformamide) and $200\text{ mM}$ trehalose offers the best results.
• Yield: A total motility of $52 \pm 12\%$ was achieved following a freezing process at $20\text{°C/min}$ and rapid thawing at $25\text{°C}$ for 15 seconds.

Sub-Zero Embryo Conservation

Beyond sperm, cryobiology has reached milestones with embryos. Servín et al. (2025b) demonstrated that it is possible to cool axolotl embryos down to $-6\text{°C}$, maintaining viable hatching rates between $18\%$ and $53\%$. This breakthrough holds disruptive potential for biobanks and translocation projects, allowing biological development to be slowed for long-distance transport.

Guide to Responsible Axolotl Husbandry in Captivity

Maintaining an axolotl (Ambystoma mexicanum) in captivity is a task that demands precision; therefore, it is not considered a pet for beginners. It is recommended that interested individuals first become familiar with the maintenance of tropical freshwater aquariums before transitioning to this species. With proper care and rigorous water quality management, an axolotl can reach a life expectancy of up to 15 years.

Optimal Water Quality Parameters

To guarantee a healthy environment, the aquarium must strictly adhere to the following physicochemical values:

Afnan et al. (2026) emphasize that low temperatures are crucial for optimal development, recommending them as the ideal growth temperature. Furthermore, they suggest the use of Ultra Recirculating Cooling Systems (URCS) to maintain thermal stability.

Innovation and Technological Monitoring

The care of this species has entered the digital era. Mochammad et al. (2026) report that the use of Internet of Things (IoT) based systems, connected to platforms such as Blynk, allows for real-time monitoring. These systems can:

• Automatically control chillers (Peltier devices) if the water exceeds $21-24\text{ °C}$.
• Alert the keeper to critical deviations in pH or hardness (TDS).

Environmental Preparation and Holtfreter’s Solution

To recreate the ideal chemical environment, Robles et al. (2009) and Sanders (2017) recommend Holtfreter’s Solution, whose composition per liter of distilled water is:

• $NaCl$ (Non-iodized salt): $3.46\text{ g}$
• $KCl$ (Potassium chloride): $0.05\text{ g}$
• $CaCl_2$ (Calcium chloride): $0.1\text{ g}$
• $NaHCO_3$ (Sodium bicarbonate): $0.2\text{ g}$
• Resulting pH: $7.4$

Aquascaping and Refuges

The aquarium design must prioritize the animal’s physical safety. Experts (Mena & Servín, 2014) recommend:

• Vegetation: Plants such as Java Fern or Java Moss. According to Ayala et al. (2019), plant cover is vital, as axolotls use it as their primary refuge during hours of peak light activity.
• Substrate: Bare bottom or extremely fine sand to prevent the accidental ingestion of gravel.

Compatibility and Coexistence: Can the Axolotl Share its Aquarium?

The golden rule in Ambystoma mexicanum husbandry is clear: the axolotl should preferably be kept as a species-only tank inhabitant. Due to its nature and specific requirements, the introduction of other animals typically leads to health issues or aggression.

Risks of Coexistence with Other Species

• Small Fish: Due to their hunting instinct and suction-feeding mechanism, axolotls will consume any small fish that fits in their mouths.
• Large or Aggressive Fish: Larger fish are often attracted to the axolotl’s feathery gills, nipping at them and causing severe injuries, infections, or chronic stress.
• Invertebrates: Hard-shelled freshwater snails pose a risk of choking or intestinal impaction if the axolotl attempts to swallow them.

Coexistence Among Axolotls (Conspecifics)

It is possible to keep more than one axolotl in the same enclosure, provided these strict guidelines are followed:

• Accident Prevention: Even among individuals of the same size, accidental bites to limbs can occur during feeding; therefore, supervision and sufficient space are recommended.
• Tank Dimensions: The space must be ample enough for each individual to have its own territory and refuge.
• Size Parity: Specimens must be of similar dimensions. A marked size disparity triggers cannibalistic behavior, where the larger individual will attack or prey upon the smaller one.

Selection Guide: Tips for Responsible Acquisition

Acquiring a Mexican axolotl requires meticulous observation to ensure the specimen is in optimal health. Based on the guidelines by Mena and Servín (2014), here are the key points to verify before making your choice:

Health and Morphology Checklist

• Skin and Coloration: The texture should be smooth and exhibit continuous coloration. Avoid specimens with lesions, scabs, hemorrhagic spots, or cotton-like whitish patches (possible signs of fungal infections).
• Limbs: Ensure it has all four complete legs. Correct anatomy includes four toes on the forelimbs and five on the hindlimbs.
• Tail: It should be intact, well-developed, and end in an aerodynamic “arrowhead” shape.
• Gills: Although size may vary, the specimen must present three firm branchings on each side of the head. They should look clean and free of any debris or crusting.

Critical Seller Information

Before finalizing the purchase, it is fundamental to obtain precise data regarding the specimen’s history. Do not forget to inquire about the following:

• Feeding Frequency: To maintain its nutritional routine and avoid the stress of a new home.
• Age and Sex: To determine its developmental stage and space requirements.
• Dietary Regime: What type of food is it currently consuming?

Common Diseases of the Axolotl

The health of Ambystoma mexicanum is intrinsically dependent on its environment. Because its skin is extremely permeable and delicate, it is prone to lacerations. It is fundamental to ensure that aquarium decorations lack sharp edges and to remove any objects that obstruct the amphibian’s mobility. According to Sanders (2017), the primary cause of skin lesions and blisters is poor water quality, a factor that renders these amphibians vulnerable to opportunistic pathogens.

Behavioral Warning Indicators

A sick axolotl will manifest subtle but progressive changes. According to Mena and Servín (2014), owners must remain vigilant for the following clinical signs:

• Swimming Alterations: Erratic movements or loss of equilibrium (balance).
• Posture: Unusual arching of the tail or body.
• Cutaneous Anomalies: Presence of masses, drastic color changes, or retained skin shedding (dysecdysis).
• General Status: Lack of appetite (anorexia) or inconsistent fecal matter.

To ensure proper management, it is necessary to identify the most recurrent conditions in amphibian clinical practice:

Chytridiomycosis: The Global Fungal Threat

The Mexican axolotl has been severely impacted by chytridiomycosis, an infectious disease caused by the pathogenic fungus Batrachochytrium dendrobatidis. This pathology is responsible for mass population declines in amphibians worldwide. According to Rebollar et al. (2020), B. dendrobatidis infection generates critical lesions in the axolotl’s dermis, which gravely alters its osmotic balance and the transfer of vital gases through the skin. These physiological dysfunctions can lead to cardiac or systemic failure if not treated opportunistically.

Recommended Treatment Protocol

To combat this infection in captive specimens, Michaels et al. (2018) suggest a therapeutic protocol based on controlled baths:

• Medication: Itraconazole (commercially known as Itrafungol).
• Concentration: Liquid preparations diluted to $0.01\%$ or $0.005\%$.
• Application: Daily immersions lasting between 7 to 15 minutes.
• Duration: A treatment cycle of seven consecutive days.

Note: It is recommended to perform these procedures under the supervision of a specialized exotic animal veterinarian to avoid toxicity from overdosing.

Saprolegniasis: Aquatic Fungal Infections

Saprolegnia spp. is a highly common pathogenic oomycete in aquatic ecosystems. This condition is visually distinguished by the appearance of a whitish, cotton-like growth on the skin and gills of affected specimens. According to Mena and Servín (2014), the progression of this disease leads to a severe clinical presentation that includes:

• Lethargy: A drastic decrease in physical activity.
• Anorexia: Total refusal of food.
• Respiratory Distress: Compromise of branchial (gill) function.
• Weight Loss: Deterioration of body condition.
• Mortality: In advanced cases without therapeutic intervention.

Suggested Therapeutic Protocol

To control this infection, specialists recommend a treatment based on controlled baths:

• Antifungal Agent: Application of itraconazole.
• Dosage: Concentration at $0.01\%$.
• Vehicle: Preparation in a $0.6\%$ saline solution.

Note: The saline solution not only helps combat the pathogen but also promotes the recovery of the axolotl’s osmotic balance in the skin.

Air Accumulation Syndrome and Buoyancy Disorders

One of the most frequent clinical issues in Ambystoma mexicanum is the anomalous accumulation of air within the body cavity. According to Sanders (2017), this syndrome manifests through evident abdominal distension, causing the specimen to float involuntarily, often in an inverted position (upside down).

Causes and Differential Diagnosis

There are two primary documented origins for this disorder:

• Pulmonary Lesions: On the other hand, Takami and Une (2018) point out that pathologies in the lung tissue are a critical cause of buoyancy disorders. In these cases, the leakage of air into the coelomic cavity (the interior of the body) alters the amphibian’s hydrostatic equilibrium, requiring a more in-depth clinical evaluation.
• Digestive Immaturity: In young specimens, the developing intestinal tract may present difficulties in processing high-protein diets. According to experts, this condition tends to resolve naturally as the specimen matures. An immediate solution consists of reducing food portions to facilitate intestinal transit.

Hydrocoeloma: The Challenge of Fluid Distension

Hydrocoeloma, clinically defined as the distension of the coelomic cavity due to fluid accumulation, is one of the most recurrent pathologies in amphibians. Research by Clancy et al. (2015) reveals a critical epidemiological datum: females exhibit an incidence rate three times higher than males. This prevalence is so significant that, in specialized markets such as Japan, hydrocoeloma has been documented as the most common disease in Ambystoma mexicanum (Takami & Une, 2017).

Etiology and Environmental Factors

Although traditionally associated with organ failure, recent studies by Cirit et al. (2025) confirm that poor water quality is the primary origin of this condition. The osmotic imbalance triggered by an inadequate environment sparks the accumulation of clear, odorless fluids within the amphibian’s abdomen.

Clinical Intervention Protocols

The treatment of hydrocoeloma requires a combination of invasive procedures and specialized pharmacology:

• Prophylaxis: Oral administration for one week to prevent secondary infections following drainage, even if the primary cause is not bacterial.
• Coelomic Paracentesis: This consists of draining the accumulated fluid. Cirit et al. (2025) propose the use of 26G insulin syringes to extract volumes of up to $10\text{ cc}$, providing immediate relief of internal pressure.
• Pharmacological Therapy: The administration of enrofloxacin is recommended.
• Standard Dosage: $10\text{ mg/kg}$ every 24 hours (Clancy et al., 2015).

Conclusions: The Future of the Guardian of Xochimilco

The Mexican axolotl (Ambystoma mexicanum) represents a biological enigma and a cultural bastion currently facing its greatest survival challenge. Nevertheless, its singular beauty and deep-seated roots in Mexican identity have catalyzed unprecedented global interest in its preservation and the refinement of specialized husbandry techniques.

As the vertebrate model system with the highest documented regenerative capacity (Caballero et al., 2018), the axolotl has established itself as the cornerstone of numerous international research laboratories. This scientific status has not only allowed the secrets of its genetics to be decoded but has also driven the development of highly sophisticated breeding protocols that ensure the species’ welfare in captivity.

Currently, the axolotl phenomenon has transcended laboratories to position itself as a high-demand species within the ornamental industry. Given this reality, it is imperative to promote and regulate sustainable axolotl aquaculture. Encouraging certified hatcheries will not only ethically satisfy global demand but also constitute a key strategy to reduce pressure on wild populations, ensuring that this “water monster” continues to amaze future generations.

Frequently Asked Questions (FAQ) about the Mexican Axolotl

References

Afnan, N. I., Faqih, A. R., & Dailami, M. (2025). The effect of temperature manipulation on the growth of axolotl (Ambystoma mexicanum). Fisheries Journal, 15(2), 849-858. http://doi.org/10.29303/jp.v15i2.1463

Aguilar J. y R. Luría. 2016. Los anfibios en la cultura mexicana. Ciencia.

Astorga de Ita, D., Morales Valdelamar, G. A., Cadena Roa, A., & Balvanera, P. (2025). Axolotl soup: Hydrocoloniality, contested foodscapes, and plural values of nature. Environment and Planning D: Society and Space, 0(0).

Ávila V., T. González, A. González, M. Vázquez. 2021. El género Ambystoma en México ¿Qué son los ajolotes? CIENCIA ergo-sum, Revista Científica Multidisciplinaria de Prospectiva, vol. 28, núm. 2, 1. DOI: https://doi.org/ces.v28n2a10

Ayala, C., Ramos, A.G., Merlo, Á. et al. Microhabitat selection of axolotls, Ambystoma mexicanum, in artificial and natural aquatic systems. Hydrobiologia 828, 11–20 (2019). https://doi.org/10.1007/s10750-018-3792-8

Caballero-Pérez Juan, Annie Espinal-Centeno, Francisco Falcon, Luis F. García-Ortega, Everardo Curiel-Quesada, Andrés Cruz-Hernández, Laszlo Bako, Xuemei Chen, Octavio Martínez, Mario Alberto Arteaga-Vázquez, Luis Herrera-Estrella, Alfredo Cruz-Ramírez. Transcriptional landscapes of Axolotl (Ambystoma mexicanum), Developmental Biology, Volume 433, Issue 2, 2018, Pages 227-239, ISSN 0012-1606, https://doi.org/10.1016/j.ydbio.2017.08.022.

Cirit, Ş. S., Deniz, Ş. B., Cirit, B., & Bayraktar, A. (2025). Management of Hydrocoelom in an Axolotl (Ambystoma mexicanum). Veterinary Medicine and Science, 11(3), e70373. https://doi.org/10.1002/vms3.70373

Clancy Meredith M., Leigh A. Clayton, and Catherine A. Hadfield “HYDROCOELOM AND LYMPHEDEMA IN DENDROBATID FROGS AT NATIONAL AQUARIUM, BALTIMORE: 2003–2011,” Journal of Zoo and Wildlife Medicine 46(1), 18-26, (1 March 2015). https://doi.org/10.1638/2014-0171.1

Coxe, N., Liu, Y., Arregui, L., Upton, R., Bodenstein, S., Voss, S. R., Gutierrez-Wing, M. T., & Tiersch, T. R. (2024). Establishment of a Practical Sperm Cryopreservation Pathway for the Axolotl (Ambystoma mexicanum): A Community-Level Approach to Germplasm Repository Development. Animals, 14(2), 206. https://doi.org/10.3390/ani14020206

Fernández, T., Martínez-Meyer, E. & Zambrano, L. A connectivity analysis to find areas for habitat restoration of the axolotl (Ambystoma mexicanum) in its natural habitat. Urban Ecosyst 28, 90 (2025). https://doi.org/10.1007/s11252-025-01700-y

Figiel C. 2020. Cold Storage of Sperm from the axolotl, Ambystoma mexicanum. Herpetological Conservation and Biology 15(2):367–371.

Figiel, Chester R., Jr. 2023. “Effects of Water Temperature on Gonads Growth in Ambystoma mexicanum Axolotl Salamanders” Animals 13, no. 5: 874. https://doi.org/10.3390/ani13050874

García-González F, Servín E, Álvarez-Guerrero AL, Alcantar-Rodríguez A and Medrano A (2025) Embryo development in Mexican axolotl (Ambystoma mexicanum): a stage morphological study. Front. Amphib. Reptile Sci. 3:1535817. doi: 10.3389/famrs.2025.1535817

Gonzalez-Santana, O. D., & Jardon-Xicotencatl, S. (2024). El ajolote de Xochimilco (Ambystoma mexicanum): Un enfoque anatómico y científico para su conservación. Boletín De Ciencias Agropecuarias Del ICAP, 10(20), 16–22. https://doi.org/10.29057/icap.v10i20.12048

Haluza, Y., Gruhl, B., Wagner, A. et al. Axolotls retain fertility throughout lifespan. BMC Biol 24, 52 (2026). https://doi.org/10.1186/s12915-026-02545-3 x

Makanae, A., Tajika, Y., Nishimura, K. et al. Neural regulation in tooth regeneration of Ambystoma mexicanum. Sci Rep 10, 9323 (2020). https://doi.org/10.1038/s41598-020-66142-2

McCusker Catherine D., Carlos Diaz-Castillo, Julian Sosnik, Anne Q. Phan, David M. Gardiner. Cartilage and bone cells do not participate in skeletal regeneration in Ambystoma mexicanum limbs, Developmental Biology, Volume 416, Issue 1, 2016, Pages 26-33, ISSN 0012-1606, https://doi.org/10.1016/j.ydbio.2016.05.032.

Manjarrez-Alcívar, I., VegaVillasante, F., Montoya-Martínez, C., E., López-Félix, E. F., Badillo-Zapata, D., & Martínez-Cárdenas, L. (2022). New findings in the searching of an optimal diet for the axolotl Ambystoma mexicanum: protein levels. Agro Productividad. https://doi.org/10.32854/ agrop.v14i6.2188

Manjarrez-Alcívar, I., Martínez-Cárdenas, L., Vega-Villasante, F., Badillo-Zapata, D., Montoya-Martínez, C. E., & López-Félix, E.F. (2024). Levels of fat for potential consumption of juvenile Ambystoma mexicanum (Shaw & Nodder, 1798) axolotls: Lipid levels. Agro Productividad. https://doi.org/10.32854/agrop.v17i4.2649

Manríquez-Guzmán, D. L., Chaparro-Herrera, D. J., & Ramírez-García, P. (2023). Microplastics are transferred in a trophic web between zooplankton and the amphibian Axolotl (Ambystoma mexicanum): Effects on their feeding behavior. Food Webs, 37, e00316.

Mena H. y E. Servín. 2014. Manual básico para el cuidado en cautiverio del axolote de Xochimilco (Ambystoma mexicanum). Instituto de Biología de la Universidad Nacional Autónoma de México. 34 p.

Michaels Christopher J., Matthew Rendle, Cathy Gibault, Javier Lopez, Gerardo Garcia, Matthew W. Perkins, Suzetta Cameron & Benjamin Tapley. 2018. Batrachochytrium dendrobatidis infection and treatment in the salamanders Ambystoma andersoni, A. dumerilii and A. mexicanum. Herpetological Journal.

Mochammad Ari Wibowo, Indah Sulistiyowati, Syamsudduha Syahrorini, Jamaluddin, Shazana Dhiya Ayuni, Malik Ubaydullaev; Smart IoT system for axolotl aquarium water monitoring and temperature control. AIP Conf. Proc. 5 January 2026; 3337 (1): 040040. https://doi.org/10.1063/5.0300572

Montoya-Martínez, C. E., Mendiola-Altamirano, T. Y., Guerrero-Galván, S. R., Huerta-Ávila, G., Ocaranza-Joya, V. S., Badillo- Zapata, D., & Vega-Villasante, F. (2022). Efecto atrayente de harinas de pescado, camarón y Spirulina para el ajolote mexicano (Ambystoma mexicanum). Revista Latinoamericana De Recursos Naturales, 18(2), 56-61. Recuperado a partir de https://revista.itson.edu.mx/index.php/rlrn/article/view/327

Naturalista. Ajolote de Xochimilco Ambystoma mexicanum.

Nowoshilow, S., Schloissnig, S., Fei, JF. et al. The axolotl genome and the evolution of key tissue formation regulators. Nature 554, 50–55 (2018). https://doi.org/10.1038/nature25458

Ocaranza-Joya, V. S., Martinez-Cardenas, L., Badillo-Zapata, D., Montoya-Martinez, C. E., Lopez-Felix, E. F., & Vega-Villasante, F. (2021). First attempt to fill gaps in the feeding of the axolotl. AGROProductividad, 14(10), 37+.

RAMÍREZ-MACAL, D. A.; CONZUELO-SIERRA, M. R.; SALAZAR-DE SANTIAGO, A.; CHÁVEZ-RÍOS, A.; DE VELASCO-REYES, I. & DÍAZ, J. M. Descripción morfométrica de la anatomía externa e interna del Ambystoma mexicanum. Int. J. Morphol., 40(2):401-406, 2022.

Ramos AG, Mena H, Schneider D, Zambrano L (2025) Movement ecology of captive-bred axolotls in restored and artificial wetlands: Conservation insights for amphibian reintroductions and translocations. PLoS ONE 20(4): e0314257. https://doi.org/10.1371/journal.pone.0314257

Randal Voss S., Hans H. Epperlein, and Elly M. Tanaka. 2009. Ambystoma mexicanum, the Axolotl: A Versatile Amphibian Model for Regeneration, Development, and Evolution Studies. Cold Spring Harb Protoc; 2009; doi:10.1101/pdb.emo128

Rebollar E. ? Los ajolotes y su microbioma ante enfermedades. CONACYT.

Rivera-Pacheco Juan, Herrera-Barragán José, León-Galván Miguel, Ocampo-Cervantes José, Pérez-Rivero Juan, Gual-Sill Fernando. Ambystoma mexicanum sperm cryopreservation (Shaw & Nodder, 1798). Abanico vet [revista en la Internet]. 2021 Dic [citado 2022 Mayo 12] ; 11: e108.

Robles Mendoza, Cecilia, García Basilio, Claudia Elizabeth, & Vanegas Pérez, Ruth Cecilia. (2009). Maintenance media for the axolotl Ambystoma mexicanum juveniles (Amphibia: Caudata). Hidrobiológica, 19(3), 205-210.

Sámano, C., González-Barrios, R., Castro-Azpíroz, M., Torres-García, D., Ocampo-Cervantes, J. A., Otero-Negrete, J., & Soto-Reyes, E. (2021). Genomics and epigenomics of axolotl regeneration. Int J Dev Biol, 65(7-9), 465-474.

Sanders J. 2017. Axolotl – Ambystoma mexicanum. PetMD.

SEMARNAT, 2018. Programa de Acción para la Conservación de las Especies Ambystoma spp, SEMARNAT/CONANP, México (Año de edición 2018).

Servín, E., Lilia, A., & Medrano, A. (2025a). Embryo development in Mexican axolotl (Ambystoma mexicanum): A stage morphological study. Frontiers in Amphibian and Reptile Science, 3, 1535817. https://doi.org/10.3389/famrs.2025.1535817

Servín E, Alcantar-Rodriguez A and Medrano A (2025b) Experiences with the management and breeding of Mexican axolotl (Ambystoma mexicanum), for research and biobanking purposes, in a vivarium. Front. Amphib. Reptile Sci. 3:1620078. doi: 10.3389/famrs.2025.1620078

Smith, J. J., Timoshevskaya, N., Timoshevskiy, V. A., Keinath, M. C., Hardy, D., & Voss, S. R. (2019). A chromosome-scale assembly of the axolotl genome. Genome Research, 29(2), 317–324. https://doi.org/10.1101/gr.241901.118

Takami Yoshinori and Yumi Une. 2017. A retrospective study of diseases in Ambystoma mexicanum: a report of 97 cases. The Journal of Veterinary Medical Science https://doi.org/10.1292/jvms.17-0066

Takami Y, Une Y (2018) Buoyancy disorders in pet axolotls Ambystoma mexicanum: three cases. Dis Aquat Org 127:157-162. https://doi.org/10.3354/dao03187

Webb, A. (2023). URBANIZATION’S IMPACT ON MEXICAN AXOLOTL (AMBYSTOMA SP.) AND STATUS OF ONGOING CONSERVATION EFFORTS.

Wikipedia. Ambystoma mexicanum.

Zambrano, L., E. Valiente y M.J. Vander Zanden. 2010. Food web overlap among native axolotl (Ambystoma mexicanum) and two exotic fishes: carp (Cyprinus carpio) and tilapia (Oreochromis niloticus) in Xochimilco, Mexico City. Biological Invasions, 12(9), 3061–3069

Milthon Lujan

Editor at the digital magazine AquaHoy. He holds a degree in Aquaculture Biology from the National University of Santa (UNS) and a Master’s degree in Science and Innovation Management from the Polytechnic University of Valencia, with postgraduate diplomas in Business Innovation and Innovation Management. He possesses extensive experience in the aquaculture and fisheries sector, having led the Fisheries Innovation Unit of the National Program for Innovation in Fisheries and Aquaculture (PNIPA). He has served as a senior consultant in technology watch, an innovation project formulator and advisor, and a lecturer at UNS. He is a member of the Peruvian College of Biologists and was recognized by the World Aquaculture Society (WAS) in 2016 for his contribution to aquaculture.