Ambystoma mexicanum (Axolotl)

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Ambystoma mexicanum (Axolotl), also called Black Melanoid, is a melanic form of the axolotl, an aquatic amphibian native to Mexico. Its permanently larval body shape, external gills and uniform black coloration make it especially distinctive in the aquarium. This variety retains the species’ basic requirements, including cool, clean and well-oxygenated water. The axolotl is generally peaceful, but it needs a carefully planned setup and compatible tankmates. This line is exclusive to Ton.Fish in Canada and represents a variety of intermediate rarity in the specialty trade.

General species description

The axolotl is a urodele amphibian that retains several larval characteristics into adulthood, a condition known as neoteny. It normally lives in water and breathes mainly through its feathery external gills, although it also has functional lungs. Its behavior is usually peaceful, and its movements are slow, with periods of stillness on the bottom. In captivity, it benefits from a spacious, dimly lit aquarium with plenty of shelters. The Black Melanoid variety is recognized by its abundant dark pigmentation and sombre appearance. Like other axolotls, it can regenerate certain tissues and limbs, but this ability does not replace proper water quality or an appropriate diet.

Geographic origin and biotope

Country of reference: Mexico. The species is native to the Mexico City basin, particularly the aquatic environments associated with Xochimilco in the Mexico Valley. Its historical habitat consisted of freshwater lakes and canals that were generally calm, shallow and rich in aquatic vegetation. The canals provided sheltered areas among plants, roots and submerged debris. The water was cool compared with that of many tropical aquariums, and the bottom could consist of mud, silt and fine material. Axolotls mainly used quiet areas where they could move along the bottom and hide during bright periods. The conservation of its natural habitat remains a serious concern.

Precise locality and local name

The species’ best-known locality is the Xochimilco canal system in southern Mexico City, within the Mexico Valley. The original local name is axolote, also written axolotl in international literature. In Mexican usage, the animal is commonly called axolote or ajolote, depending on the spelling used. Historical populations also occupied the wider Mexico lake complex, but the remaining natural range is greatly reduced. In the aquarium trade, Black Melanoid refers to a color variety rather than a distinct geographic population. The variety presented here is intended for the Canadian specialty market through Ton.Fish.

Appearance and physical characteristics

The axolotl has an elongated, sturdy body and four short legs. Its broad head has small, eyelidless eyes and three pairs of external gills positioned behind the head. The Black Melanoid variety shows a black to very dark gray coloration, with little or no visible golden shimmer. The digits are delicate, the tail is laterally compressed and continues into a caudal fin. Adults can reach a substantial size, especially when well fed and kept cool. The skin is sensitive to abrasions and unsuitable parameters. Sharp decorations, strong currents and repeated handling should therefore be avoided, as they may damage the gills and protective mucus layer.

General diet

The axolotl is an opportunistic predator that detects prey mainly through movement and smell. Its diet can include suitable earthworms, specially formulated carnivorous axolotl foods and appropriate aquatic prey. Pellets should sink and be appropriately sized for the mouth. Earthworms are an excellent staple when obtained from a clean, pesticide-free source. Uneaten food should be removed to maintain good water quality. Very fatty prey, tropical fish foods and small fish with spiny fins should be avoided. Young animals are fed more often, while adults receive meals at longer intervals according to their body condition.

Essential data

• Name of the original river: no single river; the species is associated with the lake and canal system of Xochimilco.
• Local name used: axolote or ajolote.
• Origin of the scientific name: Ambystoma is the genus name; mexicanum refers to Mexico.
• Etymology of the full name: Ambystoma comes from Greek and is generally interpreted as “closed mouth”; mexicanum means “from Mexico.”
• Common/vernacular names: axolotl, axolote, ajolote, Mexican salamander; Black Melanoid for the variety.
• Family: Ambystomatidae.
• Subfamily: Ambystomatinae.
• Name pronunciation: am-bis-TOH-ma mex-ih-KAH-num.
• Discovery: scientifically described by George Kearsley Shaw and Frederick Polydore Nodder in 1798.
• Maximum adult size: approximately 30 cm.
• Water temperature and pH: approximately 16 to 20 °C; pH around 7.0 to 7.5.
• Watercourse appearance and surrounding vegetation: calm, shallow canals with freshwater, dense aquatic vegetation, roots and muddy areas.
• Typical tankmates: best kept alone or with similar-sized axolotls; fish are not recommended as regular tankmates.
• Temperament and behavior: generally calm, discreet and most active at dusk or under subdued lighting.
• Water depth: shallow natural environments; in aquariums, enough height for easy movement and convenient access to the surface.
• Sexual dimorphism: adult males generally have a more developed cloacal region, while females often have a broader body.
• Bottom structure and flow: fine, non-abrasive bottom material with no gravel that can be swallowed; low to moderate flow with good oxygenation.

In your aquarium

To succeed with Ambystoma mexicanum (Axolotl), provide a stable, cool and well-filtered aquarium without unnecessary heating or intense lighting. Very fine sand or a bare-bottom aquarium reduces the risk of ingestion and makes maintenance easier. Offer shaded areas, regularly monitor ammonia, nitrite and nitrate, and feed high-quality meaty foods. Avoid tankmates that are too small, aggressive or likely to nip the gills. Prolonged high temperatures are particularly harmful. With clean water, gentle flow and an appropriate diet, this axolotl can remain a fascinating and long-lived inhabitant of an aquarium designed specifically for its needs.