黑帝王魟 · Black Stingray

Overview

Potamotrygon henlei, P12, has white or yellow spots over a dark brown to black disc, with considerable variation in spot size and number. It requires a large mature system, rigorous maintenance, and dependable feeding. Juvenile size does not represent its permanent housing needs.

Distribution & habitat

It is probably restricted to Brazil's Tocantins basin. Like relatives, it uses sandbars, river shallows, and slow tributaries over sand or mud, entering flooded forest seasonally and sometimes remaining in pools as water retreats.

Aquarium setup

Allow at least about 240 × 120 × 60 cm for an adult. Preserve extensive open floor space. Any wood or smooth rocks should be secured or heavy enough to resist displacement. Subdued light is preferable. Rooted plants may be eaten, and even attached plants are not guaranteed to survive.

River sand particularly suits juveniles and permits burial when alarmed. A bare bottom simplifies cleaning but removes that refuge. Provide strong mature biological filtration through a sump or suitable external filters. Around four tank volumes per hour is a circulation reference; surface disturbance helps maintain high oxygen levels.

Keep equipment outside the occupied area or protected, especially heaters that could burn a resting ray. Change about 50% weekly and prevent nitrogenous-waste accumulation. Fit a close cover because feeding rays may rise well above the surface.

Diet & feeding

Freshwater rays generally eat fish and aquatic invertebrates. Offer a varied animal-based menu at least twice daily. Juveniles take bloodworms, Tubifex, brine shrimp, and krill; adults need appropriately sized fish, shellfish, shrimp, squid, and earthworms. Avoid reliance on one food.

New arrivals may be thin and refuse frozen fare. Live bloodworms or suitably sized earthworms can establish feeding before gradual conversion to nonliving foods once condition improves. Avoid beef heart, chicken, and other mammalian or bird meat. Routine feeder fish are unnecessary and add disease or parasite risks.

Behaviour & compatibility

Predation makes most small companions unsafe, while aggressive or territorial fishes can also undermine ray health. Tankmates must be too large to swallow, peaceful, and preferably use upper water. Large bottom dwellers add substantially to floor-space needs.

Smaller fish such as discus have reportedly been taken at night. Large suckermouth catfish may attach to and injure the disc, so a cleanup role does not guarantee safety. Related rays may hybridize; retain identity and provenance in breeding groups.

Sexual dimorphism

Males possess a backward-pointing clasper along the inner edge of each pelvic fin. These mating structures are smaller but still visible in juveniles.

Breeding

Captive reproduction of this species is established. Young develop inside the female and receive uterine secretions after yolk reserves are exhausted, emerging fully formed. Simply combining a male and female does not guarantee a pair. Natural pairing from youngsters requires substantial space and years of patience.

Choose a female larger than the male. Courtship involves chasing, biting the disc margin, and moving beneath her; unsuccessful prolonged pursuit can injure her, so prepare separation facilities. Fertilization is internal. General captive experience in the genus gives gestation around nine to twelve weeks, with markedly increased feeding needs for the female.

Separate newborns to reduce predation or injury. Birth can cloud the water; after moving pups, make a substantial water change. Their yolk reserves may last up to about a week, followed by several daily meals of quality live or frozen food. Mixing live items can encourage acceptance of frozen fare. Rest females away from males after two or three litters. Young of this species are mottled brown, without the adult's bright contrast.

Notes

Potamotrygon leopoldi and P14 are similar. Underside spots help comparison but are not an absolute test. Defensive spines remain hazardous after shedding. Do not pet rays or catch them in nets; use a solid container or large fish bag, and watch for shed spines during cleaning. Seek medical care after a sting.

Confirm feeding before acquisition. Prominent structures beside the tail base or a hollow between the eyes suggest poor condition. Persistently curled disc edges are a serious abnormality.