West African Mud Turtle

West African mud turtle（圖片來源：Loran，採用 CC BY 2.0 授權）

The West African mud turtle (Pelusios castaneus) is a medium-sized freshwater turtle distributed across West and Central Africa. One of its defining features is its inability to retract its head straight back into the shell; instead, it bends its neck sideways and tucks it along the shell margin, giving rise to the name “side-necked turtle.” Females can reach up to 28 cm in carapace length, while males are slightly smaller at around 25 cm. The carapace is typically dark brown to black, though coloration varies depending on habitat. Patterns along the carapacial keels and the coloration of the plastron may differ between individuals inhabiting rainforests and savanna regions. Beyond their appearance, these turtles are highly tolerant of environmental variation, making them one of the more adaptable reptiles in African freshwater systems.

In the wild, the species is widely distributed across countries such as Senegal, Guinea, Ivory Coast, Ghana, Cameroon, the Congo, and Angola, spanning environments from coastal West Africa to Central African forests. They inhabit a wide range of freshwater habitats, including streams, ponds, swamps, and lakes. During the dry season, they may burrow into mud and enter a state of estivation to avoid desiccation. This ability allows them to persist in environments where water bodies periodically disappear.

Behaviorally, they may be either diurnal or nocturnal. Juveniles tend to remain hidden among aquatic vegetation and rarely bask, whereas adults frequently gather along shorelines or on floating logs during the day to bask, maintaining body temperature and metabolic function. When foraging, they dive to the bottom and rapidly extend their necks to capture aquatic insects, crustaceans, fish, and snails. They also consume some aquatic plants, making them omnivorous. Their broad diet and behavioral flexibility position them as both mid-level predators and scavengers within local freshwater ecosystems.

Under proper care, West African mud turtles can live for more than 50 years, making them long-term companion animals. Prospective keepers must recognize that keeping this species represents a long-term commitment rather than a temporary interest.

West African mud turtle（圖片來源：Valeriefarias，採用 CC BY-SA 4.0 授權）

Housing Requirements in Captivity

To provide a suitable captive environment, conditions should replicate their native African aquatic habitats. As a highly aquatic species, water should occupy the majority of the enclosure. A single adult requires at least a 150-liter aquarium, with larger volumes needed for multiple individuals. Water depth should be approximately 15–20 cm, allowing free swimming while enabling easy access to the surface for breathing.

Water quality is critical to health. Although this species tolerates relatively turbid conditions, captive environments should maintain clean water to reduce the risk of skin disease and infection. A strong filtration system combined with regular water changes is ideal. If relying primarily on water changes, partial changes should be performed every 2–3 days, with more than half the volume replaced every two weeks. Optimal pH ranges from 6.8 to 7.0, ammonia and nitrite levels should be as close to zero as possible, and dissolved oxygen should be maintained above 6 ppm.

In addition to the aquatic area, a dry basking platform must be provided. This can be constructed using driftwood, flat stones, or artificial platforms, allowing occasional emergence from the water. Above this area, ultraviolet (UVB) lighting and a heat lamp should be installed. Daytime ambient temperatures should be maintained at 26–28°C, with basking areas reaching 32–35°C to simulate natural sun exposure. Nighttime temperatures should not fall below 24°C; heaters or insulation may be used if necessary.

The enclosure should also include hiding spaces, as these turtles naturally seek shelter among aquatic plants or sediment. Submerged plants, driftwood, or artificial vegetation can be added to reduce stress and minimize aggression between individuals. Because they sometimes dig, the terrestrial section should contain a sufficiently deep substrate of sand or soil, which also provides a suitable site for egg-laying and mimics natural behavior.

Feeding Conditions

The West African mud turtle is omnivorous, and its diet should include both animal and plant matter. Juveniles require higher protein intake and can be fed small fish, shrimp, insects, earthworms, or commercial turtle pellets. Adults should gradually shift toward a plant-dominant diet, which may comprise up to 80% of total intake. Suitable plant foods include leafy greens such as non-head lettuce, dandelion greens, mustard greens, and carrot tops, as well as occasional duckweed or aquatic plants.

Animal-based foods may include frozen freshwater fish, shrimp, or small mollusks. High-fat meats or large fish with bones should be avoided to prevent digestive or renal issues. Commercial turtle pellets can be used as a supplement but should not replace fresh foods entirely. Feeding is best conducted in water, as these turtles are adapted to swallowing food while swimming. However, this can rapidly degrade water quality, so many keepers use a separate feeding container and return the turtle to the main tank afterward to reduce maintenance.

Juveniles can be fed daily, whereas adults should be fed once every 2–3 days. The quantity per feeding should be limited to what can be consumed within a few minutes to prevent obesity and water fouling. Supplementation with calcium and vitamin D3 is recommended, particularly during growth stages and for breeding females, as these are essential for bone development and eggshell formation.

Breeding Conditions

In the wild, reproductive timing varies depending on regional climate. Some populations lay eggs during the dry season, others near the onset of the rainy season, and some may reproduce twice annually. Females reach reproductive maturity at a carapace length of approximately 12 cm and can lay several to more than twenty soft-shelled white eggs per clutch. These eggs are typically buried in loose soil, requiring high humidity (around 95%) and appropriate temperatures for incubation.

In captivity, if egg-laying behavior is observed, keepers should provide a deep, moist substrate to allow natural nesting. Fertilized eggs can be carefully transferred to an incubator using moist vermiculite or perlite as a substrate, maintaining high humidity and temperatures between 27 and 29°C. This species exhibits temperature-dependent sex determination: incubation below 26°C or above 29°C tends to produce females, while temperatures between 27 and 28°C yield predominantly males.

Incubation typically lasts 50–60 days. Hatchlings are very small and should be housed in shallow water, approximately 2–4 cm deep, with aquatic plants providing cover. They can initially be fed small insects or chopped earthworms, with diet diversity increasing as they grow. Hatchlings should not be housed with adults, as adults may attack or even prey upon them.

Preventing Invasive Spread

Native to West and Central Africa, the West African mud turtle is present in the pet trade. When improperly released into non-native environments, it can cause serious ecological disruption. Established populations have already been reported in places such as Guadeloupe in the Caribbean, where introduced individuals threaten native freshwater turtles.

Therefore, keepers must follow the principle of “no abandonment and no release”. If unable to continue care, the appropriate course of action is to transfer the animal to a responsible keeper or contact a legal animal shelter or rescue organization. Releasing individuals into the wild not only harms local ecosystems but may also result in the animal's death due to unsuitable environmental conditions.

Author: Shui-Ye You