Species Overview

Common name: Axolotl, Mexican walking fish
Scientific name: Ambystoma mexicanum
Origin: Native to the freshwater lakes and canals of Xochimilco, Mexico
Lifespan: 10–15+ years with correct care

Adult Size

  • Typically 23–30 cm (9–12 inches)

Temperament

  • Calm, curious, and docile

  • Best observed rather than handled

  • Stress easily from excessive handling or poor water conditions

Activity

  • Primarily crepuscular/nocturnal (most active at dusk and during the night)

Housing & Aquarium Setup

Tank Size

Axolotls require cool, well-filtered aquariums with plenty of floor space.

  • Minimum for one adult: 3ft tank (around 75–100 litres)

  • Recommended: 4ft tank for one adult or multiple axolotls

More space improves water quality and overall health.

Substrate

Best options:

  • Fine sand (axolotl-safe)

  • Bare-bottom tanks (Mainly for juveniles)

Avoid:

  • Gravel, stones, or anything smaller than the axolotl’s head (risk of impaction)

Furnishings & Enrichment

  • Smooth hides (caves, PVC pipes, slate)

  • Soft, silk or live plants for cover

  • Gentle water flow only

  • Shaded areas to avoid light stress

All décor should have no sharp edges.

Water Parameters & Temperature

Temperature

  • Ideal range: 16–18°C

  • Maximum: 20°C (short-term only)

Cooling may be required in warmer months (fans or aquarium chiller).

Water Quality

  • Ammonia: 0 ppm

  • Nitrite: 0 ppm

  • Nitrate: <20 ppm

  • The tank must be fully cycled for about 2 weeks before introducing an axolotl.

Filtration

  • Use a filter rated for a larger tank but with low flow

  • Sponge filters or spray bars are ideal

Lighting

  • Axolotls do not require UVB

  • Low-level ambient lighting only

  • Avoid bright lights and direct sunlight

Diet & Feeding

Diet

Axolotls are carnivorous.

Staple foods:

  • Earthworms (nightcrawlers) – best staple

  • Axolotl or carnivore pellets

Occasional foods:

  • Bloodworms (treat only)

  • Blackworms

  • Small pieces of raw prawn or fish (very occasional)

Avoid:

  • Feeder fish

  • Insects with hard shells

  • Mammal or reptile foods

Feeding Frequency

  • Juveniles: Daily

  • Adults: 2–3 times per week

Remove uneaten food promptly to maintain water quality.

Handling & Behaviour

  • Handling should be avoided wherever possible

  • Axolotls have delicate skin and external gills

  • If movement is necessary, use a soft container rather than hands

Stress signs include:

  • Curled gills

  • Floating

  • Reduced appetite

Cleaning & Maintenance

Daily

  • Check temperature

  • Remove uneaten food

  • Observe behaviour and gill condition

Weekly

  • 20–30% water change using dechlorinated water

  • Light substrate cleaning, if applicable

Monthly

  • Rinse filter media in tank water (never tap water)

Health & Welfare Monitoring

Gill Changes & Morphing

Axolotls should retain their feathery external gills throughout their lives. Loss or shrinking of gills is not normal and is usually a sign of stress or unsuitable conditions rather than true “morphing.”

Common causes include:

  • Poor water quality (ammonia or nitrites present)

  • High temperatures

  • Strong water flow

  • Frequent handling or stress

  • Inadequate oxygenation

In rare cases, axolotls can partially morph due to extreme stress, hormonal changes, or exposure to certain substances. This may involve gill reduction and changes in behaviour. Fully morphed axolotls become terrestrial salamanders and require completely different care, but this is uncommon and preventable with correct husbandry.

Maintaining cool, clean, well-oxygenated water is the best way to ensure healthy gills.

Common Health Issues

  • Heat stress: Lethargy, floating, curled gills

  • Fungal infections: White, cotton-like growths

  • Impaction: Caused by gravel ingestion

  • Poor water quality: Leads to stress and illness

Regular monitoring of water parameters, appetite, and behaviour is essential for long-term health.