Chelydra serpentina

Large aquarium, paludarium or (ideally) a semi-aquatic outdoor pond

Minimum dimensions for a single adult; an outdoor pond of several thousand litres is strongly preferable. Little land area is needed (only the female comes out to lay), but provide a zone giving access to the surface and shallow supports. LEGAL WARNING: in the European Union, Chelydra serpentina is on the list of invasive alien species of Union concern — keeping, breeding, transport and sale are prohibited, except by derogation for specimens held before the listing. Be sure to check local/national regulations before any acquisition.

A largely irrelevant parameter: an aquatic species. The air humidity above the water remains naturally high; the priority is water quality and temperature, not ambient humidity.

Avoid small-sized gravel, which is ingestible and causes impactions. A bare bottom simplifies maintenance of a very messy species; in the wild, the animal likes to burrow into a loose substrate. Wild-caught individuals are often parasitised and stressed: favour animals of legal, traceable origin.

UVB recommended for indoor keeping (5-6% tube / T5) above an emergent area, especially for juveniles, in order to synthesise vitamin D3 and prevent osteodystrophy. Less critical in adults if the diet is balanced, varied and rich in whole prey and calcium. In an outdoor pond, direct sunlight is sufficient.

The central point of husbandry: clean, dechlorinated and heavily filtered water (a very messy species), with regular changes. A depth allowing the animal to reach the surface with its neck extended — it is a poor swimmer: a real risk of drowning in deep water without a shallow area, support or access slope. Temperature 20-26°C; hides and shallow zones appreciated.

North America: from east of the Rocky Mountains and southeastern Canada down to the Gulf of Mexico. Introduced and considered invasive in several regions, notably in Europe.

Opportunistic omnivore / scavenger (strongly carnivorous) — Whole fish, earthworms, crayfish, insects, amphibians, small mammals and birds, carrion; aquatic plants.

Juveniles are mainly carnivorous; the plant portion increases with age. Offer a varied diet based on whole prey and aquatic plants, with a calcium supplement (cuttlebone). Avoid overfeeding (obesity, hepatic lipidosis) and fatty, monotonous diets (goldfish = fat + thiaminase). Indicative schedule: juveniles daily, adults 2-3 meals per week.

Clutch 20–80 eggs/young. Late maturity (often >5-10 years). Laying in spring/summer: the female leaves the water and digs a nest in an open area; spherical eggs (ping-pong-ball type). Incubation ~55-125 days depending on temperature, with temperature-dependent sex determination (TSD), typical incubation ~26-29°C. Captive breeding is rare and, in the EU, regulated/prohibited under invasive-species legislation.

• Osteodystrophy / metabolic bone disease (calcium/D3 deficiency, soft or deformed shell), especially in juveniles
• Shell rot and skin ulcers linked to poor water quality
• Aural abscesses (ear infections), often associated with vitamin A deficiency and poor water quality
• Obesity and hepatic lipidosis from overfeeding and an overly fatty diet
• Respiratory infections (water too cold, stress) and frequent parasitism in wild-caught individuals