Freshwater Motoro Stingray (Potamotrygon motoro)

Scientific Name: Potamotrygon motoro

Common Name: Freshwater Motoro Stingray

Family: Potamotrygonidae

Order: Myliobatiformes

Native Habitat: The Freshwater Motoro Stingray is native to the slow-moving rivers and tributaries of the Amazon and Orinoco basins in South America, including countries like Brazil, Colombia, Venezuela, and Peru. It typically inhabits soft, muddy riverbeds, where it hides among the substrate and relies on its camouflage to avoid predators.

Physical Characteristics

Size: The Freshwater Motoro Stingray is a large species, with males generally growing to around 35-40 cm (14-16 inches) in disc width, and females reaching up to 50 cm (20 inches). In the wild, they can grow even larger, with some individuals reaching up to 60 cm (24 inches) in disc diameter.

Appearance: This stingray has a distinctive, circular, flat body, often referred to as a "disc" shape. Its back is covered with small, smooth, and somewhat leathery skin, typically adorned with a pattern of spots or bands, which can vary from brown to gray, with darker spots or markings. The coloration provides excellent camouflage against the riverbed substrate. The underside is pale and smooth.

Tail: The tail of the Freshwater Motoro Stingray is long and thin, extending beyond the disc. It has a venomous barb used for self-defense. The stingray uses its tail to defend itself from predators, but it is generally non-aggressive unless provoked.

Behavior and Ecology

Feeding Habits: The Freshwater Motoro Stingray is a bottom-dwelling, carnivorous species. It primarily feeds on small invertebrates, crustaceans, mollusks, and small fish found along the riverbed. The stingray uses its specialized mouth, located on the underside of the disc, to sift through the mud and sand, searching for food. Its flat body helps it blend into the substrate, and its electroreceptors detect the faint electrical signals emitted by prey.

Social Behavior: Motoro Stingrays are generally solitary in the wild, but in captivity, they may tolerate the presence of other non-aggressive species. They are most active at night (nocturnal) and often hide during the day, resting in the substrate. These stingrays prefer calm, low-flow waters but are known to be adaptable to various water conditions.

Reproduction: The Freshwater Motoro Stingray is an ovoviviparous species, meaning that the female gives birth to live young, rather than laying eggs. The gestation period is around 4-6 months, and the females typically give birth to 2-6 pups. The pups are born fully formed and able to swim immediately. They grow quickly, though they will need a carefully monitored environment to thrive.

Care and Maintenance in Captivity

Aquarium Setup: Keeping a Freshwater Motoro Stingray in captivity requires a large tank with sufficient space to accommodate its size. A minimum tank size of 180 gallons (around 680 liters) is recommended for a single stingray. The tank should have a sandy or fine gravel substrate, which mimics its natural riverbed environment. Motoro Stingrays are bottom-dwellers, so ample hiding places, such as smooth rocks or driftwood, should be provided for the fish to retreat to when they need rest.

Water Conditions:

• Temperature: 24-28°C (75-82°F)
• pH: 6.5-7.5 (slightly acidic to neutral)
• Hardness: Soft to moderately soft water (under 10 dGH)
• Filtration: A strong, but gentle filtration system is necessary to maintain clean water, as the Motoro Stingray’s large tank will require regular filtration. However, the filtration should not create strong currents that could disturb the stingray.

Tankmates: The Freshwater Motoro Stingray can be kept with other peaceful, large species that are not small enough to be considered prey. Avoid keeping them with overly aggressive or territorial species. Other species of South American freshwater fish, such as large catfish or non-aggressive cichlids, can coexist with the stingray. It's important to avoid keeping smaller species that may be attacked or nipped by the stingray's tail.

Diet in Captivity: In captivity, the Freshwater Motoro Stingray should be fed a diet rich in meat-based foods, including frozen or live foods such as bloodworms, shrimp, earthworms, and small fish. It is important to ensure that the food is cut into appropriate sizes for the stingray to consume easily. Providing a varied diet helps maintain the health of the stingray and ensures that it receives the necessary nutrients.

Unique Traits

Venomous Tail Barb: Like most stingrays, the Freshwater Motoro Stingray has a sharp, venomous barb located on its tail, which is used primarily for self-defense. While the stingray is typically non-aggressive, it can use its barb to deliver a painful sting if it feels threatened. The venom from the stingray’s barb is not usually fatal to humans but can cause intense pain, swelling, and in some cases, infection.

Electrosensory Abilities: Motoro Stingrays, like other members of the Potamotrygonidae family, possess electroreceptors in their snouts, which help them detect electrical signals emitted by their prey. This ability is vital for hunting in murky waters where visibility is low. They can sense the movement of small invertebrates and fish on or near the riverbed.

Conservation Status

IUCN Status: The Freshwater Motoro Stingray is not currently listed as endangered, but its population is impacted by habitat destruction, pollution, and the aquarium trade. The loss of natural habitats and overfishing in some areas pose threats to its survival in the wild. Sustainable breeding programs in captivity are important to help protect wild populations.

Captive Breeding: Breeding the Freshwater Motoro Stingray in captivity is challenging due to the need for specific water conditions and a balanced diet. However, some breeders have successfully bred them in aquarium environments, which helps reduce the pressure on wild populations and makes the species more readily available in the aquarium trade.

In Summary

The Freshwater Motoro Stingray is an impressive and beautiful species that stands out due to its striking appearance and unique behavior. Known for its large, circular disc shape and spotted pattern, this stingray is an excellent addition to the aquarium for experienced hobbyists who can meet its care requirements. Although it requires a large, well-maintained tank and specific water conditions, the Freshwater Motoro Stingray can thrive in captivity and become a captivating centerpiece in any aquarium setup. With the proper environment and care, this remarkable species can live a long, healthy life, offering aquarium enthusiasts the opportunity to witness the fascinating behavior of a truly exotic fish.