Potamotrygon sp. "pearl" · Pearl Ray

Overview

Potamotrygon sp. 'Pearl' is a large freshwater ray traded under a provisional name. Pale markings range from golden to nearly white, while darker pattern coverage and shade vary considerably. Pattern diversity does not settle species boundaries; provenance and breeding records matter too.

Distribution & habitat

Known collections come from Brazil's Tapajós. It probably uses sandbars, river shallows, and sandy or muddy tributaries like its relatives. Seasonal movement into flooded forest and retreating-water pools is comparative information rather than a complete observation of every Pearl collection site.

Aquarium setup

Provide at least about 240 × 90 × 75 cm for an adult or pair, with additional width and length beneficial. Preserve extensive open floor space. Any wood or smooth stones must be secure. Dim lighting is suitable; rooted plants may be eaten and attached plants may also fail to persist.

River sand offers burial cover for juveniles or alarmed fish, while a bare base simplifies cleaning. Heavy waste production demands strong mature biological filtration. A sump keeps equipment away from the rays; suitable external filters are another option. About four tank volumes per hour is a circulation reference, with surface agitation for oxygenation.

Change about 50% weekly and prevent nitrogenous-waste accumulation. Isolate heaters to avoid contact burns. Secure the cover because feeding rays can emerge above the surface.

Diet & feeding

Fish and aquatic invertebrates are common foods for related rays. Offer varied animal fare at least twice daily. Juveniles take bloodworms, Tubifex, brine shrimp, and krill; adults need suitable fish flesh, whole shrimp, shellfish, squid, and earthworms.

Thin arrivals may refuse frozen foods. Establish feeding with live bloodworms or earthworms before gradual conversion once condition improves. Avoid beef heart, chicken, and other mammalian or bird meat. Routine feeder fish are unnecessary and increase parasite or pathogen risks.

Behaviour & compatibility

Small fishes may become prey, while aggressive or territorial tankmates can undermine ray condition. Prefer sufficiently large, peaceful upper-water companions. Other large bottom dwellers require additional floor space.

Smaller fishes such as discus have been taken at night, and some large suckermouth catfish injure discs by attaching to them. Another keeper's successful combination does not guarantee safety. Related species or provisional ray forms can hybridize; preserve sources instead of merging breeding groups casually.

Sexual dimorphism

Males have paired claspers extending backward along the inner pelvic-fin margins, visible in smaller form in juveniles.

Breeding

Relatives use live birth with continued maternal nourishment, with uterine secretions feeding embryos after yolk reserves are consumed. Breeding experience emphasizes mutual pair acceptance and females larger than males rather than arbitrary combinations of sexes.

Males chase, bite the disc, and slide beneath females during courtship. Prolonged unsuccessful attempts can injure them, so prepare separation facilities. Fertilization is internal. General captive gestation is often nine to twelve weeks, with increased food demand during pregnancy; this is not a fixed timetable for every Pearl pair.

Separate newborns for rearing. If birth clouds the water, make a substantial change after transferring pups. Yolk may support them for about a week, followed by several daily meals of quality live or frozen food. A little live food can encourage acceptance of frozen fare. Rest females apart from males after two or three litters to limit depletion.

Notes

The historical code R080 helps trace trade records but is not a formal scientific name. Individual patterns alone do not establish different species.

Defensive spines remain hazardous after shedding. Avoid petting and nets; use a solid container or large fish bag, and seek medical care after a sting. Confirm feeding before purchase. Hollows between the eyes, prominent tail-base structures, or persistent disc curling are abnormal signs.