Mata Mata

Mata mata（圖片來源：Dick Culbert from Gibsons, B.C., Canada，採用 CC BY 2.0 授權）

The mata mata (Chelus fimbriatus) is a freshwater turtle native to the Amazon and Orinoco River basins of South America. Its distribution includes Venezuela, Colombia, Ecuador, Peru, Bolivia, northern Brazil, and extends to Guyana, French Guiana, and Trinidad. In the wild, this species inhabits slow-moving rivers, swamps, and still water bodies, where the water is typically turbid and rich in organic matter. These environments are often acidic, with soft substrates covered in leaf litter, providing excellent camouflage.

One of the most distinctive features of the mata mata is its flattened, broad head covered with flaps of skin and protrusions. Combined with three ridges along the carapace and a dark brown shell, its appearance closely resembles submerged leaf litter or decaying wood. This remarkable camouflage allows it to avoid predators while functioning as an efficient ambush predator. Mata mata turtles remain motionless on the substrate, waiting patiently for prey. When small fish or aquatic invertebrates approach, they rapidly open their mouths, generating strong negative pressure using their throat muscles to suck in both water and prey. This feeding mechanism is known as suction feeding. Due to the structure of their jaws, they cannot chew, and prey is swallowed whole.

This species is relatively sedentary, moves slowly, and is not a strong swimmer. Instead, it walks along the bottom using its limbs. Adults can reach a carapace length of up to 45 cm and weigh over 17 kg. Sexual dimorphism is evident in the plastron and tail: males have a concave plastron and a thicker, longer tail, while females have a flatter plastron and a shorter, narrower tail. The lifespan of wild populations is not fully known, but individuals in captivity can live between 40 and 75 years, or even longer.

Reproduction typically occurs after the rainy season. Males display courtship behavior by extending their limbs, opening their mouths, and moving the skin flaps on their heads. Females lay eggs in nests dug into soft organic soil or along riverbanks. Each clutch contains approximately 12 to 28 nearly spherical eggs with hard shells, about 3.5 cm in diameter. The incubation period lasts around 200 days. Hatchlings emerge independently without parental care.

Mata mata（圖片來源：J. Patrick Fischer，採用 CC BY-SA 3.0 授權）

Housing Requirements in Captivity

Successful captive care requires replicating the natural habitat as closely as possible. Mata mata turtles prefer shallow, still, or slow-moving water. The enclosure should provide sufficient water volume, but not excessive depth. For adults, an aquarium at least 120 cm in length is recommended, with a water depth of 20–25 cm, allowing the turtle to extend its neck to breathe easily at the surface. Juveniles should be kept in shallower water, around 8–10 cm, to prevent drowning due to their limited swimming ability.

Water quality is a critical factor for health. Mata mata turtles prefer acidic water, with a pH of 5.0–6.0. Adding leaf litter, peat, or driftwood can release tannins, creating a blackwater environment similar to their natural habitat. Water temperature should be maintained between 26–30°C and kept stable to avoid respiratory illnesses. Filtration must be strong enough to handle uneaten food and waste, but water flow should remain gentle to avoid disturbing their calm behavior.

The enclosure substrate should consist of fine sand or soft mud to prevent injury to their delicate plastron and skin flaps. Driftwood, branches, and aquatic plants can provide hiding places and reduce stress. Since mata mata turtles rarely leave the water, a large basking area is not essential, though a floating log or platform can be provided occasionally. Lighting should maintain a normal day-night cycle, and UVB lighting along with a heat source is recommended to support calcium metabolism and overall health.

Feeding Conditions

Mata mata turtles are carnivorous and primarily feed on small fish and aquatic invertebrates. In captivity, live fish such as guppies, small shrimp, loaches, or mosquito fish are suitable staple foods. Live prey helps stimulate their natural hunting response and provides balanced nutrition. Earthworms, crickets, and snails can also be offered occasionally, but a varied diet is important to prevent nutritional imbalance.

Because they swallow prey whole, the size of food items must be appropriate to avoid choking. Newly imported or stressed individuals may refuse food; in such cases, offering active live fish can encourage feeding. Some keepers inject medication or supplements into feeder fish to administer treatments indirectly.

Feeding frequency varies with age. Juveniles can be fed daily to support rapid growth, while adults should be fed every 3–4 days. Overfeeding can lead to obesity and deterioration of water quality. Since mata mata turtles do not actively chase prey, offering multiple small fish at once allows them to feed at their own pace.

Breeding Conditions

Breeding mata mata turtles in captivity is challenging, though it has been achieved in some cases. Mature males perform courtship displays by extending their limbs, opening their mouths, and repeatedly moving the skin flaps on their heads to attract females. After successful mating, females typically lay eggs between October and December, selecting soft organic or sandy substrates.

A nesting area with approximately 30 cm of moist sand or soil should be provided. Each clutch contains about 12–28 hard-shelled, nearly spherical eggs. Incubation temperature should be maintained at 28–29°C, with an incubation period of 180–200 days. Due to the long incubation duration, stable temperature and humidity are essential to prevent embryo mortality.

Hatchlings receive no parental care and must be transferred immediately to a safe, shallow-water enclosure. Water depth should remain low to facilitate breathing. Newly hatched individuals often display reddish or orange markings on the plastron, which gradually fade as they grow.

Preventing Invasive Spread

Although native to South America, mata mata turtles are popular in the international pet trade due to their unique appearance. This popularity has led to cases of release or abandonment in non-native regions. Individuals have been recorded in drainage systems in Florida, USA. While no established breeding populations have been confirmed, these occurrences suggest human-mediated introduction.

If the species establishes in non-native environments, it could threaten local freshwater ecosystems and potentially introduce pathogens, impacting native fish and aquatic invertebrates.

Therefore, keepers must adhere strictly to the principle of "no release, no abandonment." Under no circumstances should mata mata turtles be released into the wild, regardless of size, care difficulty, or other reasons. If keeping the animal is no longer possible, it should be transferred to a legal animal rescue facility or an experienced keeper.

Author: Shui-Ye You