Ocellate River Stingray

About

Safety first, because this is the one entry in the catalogue where getting it wrong sends a person to hospital. The tail carries one or more barbed spines fed by venom glands, and a sting is a serious human injury, not a scare story. Seriously Fish describes a protein-based venom that causes intense pain and rapid tissue necrosis, and reports over 2000 injuries a year and the occasional death from ray stings in Colombia alone. The peer-reviewed review by Haddad, Cardoso and Garrone Neto in the Journal of Venomous Animals and Toxins including Tropical Diseases puts it clinically: the stingers are covered by toxin-producing glandular tissue, so each sting causes intense inflammation, excruciating pain and skin necrosis, particularly with freshwater rays - injuries of high morbidity and low lethality. Maidenhead Aquatics adds two practical points most keepers miss: move a ray by herding it into a solid container, never a net, and remember that shed stingers, which are replaced every two or three months, stay venomous in the tank for some time. If you are stung, seek medical help immediately. Rays are not aggressive - Heiko Bleher writes in Practical Fishkeeping that they are usually docile and curious and 'not dangerous unless stepped on or threatened' - but a startled 10 kg animal in a tank you have both hands in is a different proposition. Then the size. The disc alone reaches 60 cm across, not counting the tail - that is Maidenhead's figure and the one the 2024 IUCN assessment uses, and the one this entry follows; FishBase's own maximum is 50 cm disc width, while Seriously Fish gives up to 90 cm depending on locality and calls that exceptional in an aquarium. FishBase also carries a reported total length of 100 cm and a maximum published weight of 34.2 kg. Seriously Fish's minimum for one adult or a pair is 240 x 90 x 75 cm - 1700 litres. That is not a tank you buy; it is a room you commit. One last thing before the shop: this fish comes with paperwork. Colombia has listed Potamotrygon motoro on CITES Appendix III by name, and Brazil has listed its entire Potamotrygon population, a listing Aquarium Glaser dates to January 2017. Appendix III is a trade-cooperation listing rather than a ban - Wikipedia's summary of the convention is that trade in an Appendix III species standardly requires a CITES export permit from the country that listed it, or a certificate of origin from anywhere else. That is a rule about moving the animal across borders. Whether you may keep a venomous animal at all is decided by your own country's law, and those rules differ from one jurisdiction to the next, so check where you live before you buy rather than after.

Care

1700 litres and a 240 x 90 cm floor for one adult, because floor area, not height, is what a ray uses. Soft sand or a bare base - grit and sharp gravel abrade the disc - with any hardscape heavy, secure and taking up as little floor as possible. Sump filtration is the sane choice: it keeps heaters out of the tank, where a resting ray will burn itself on them. Turn the volume over about four times an hour, keep oxygenation high, and change around 50% weekly; the two care authorities split here: Maidenhead says a ray will not tolerate an elevated nitrate level, while Seriously Fish holds that they withstand fairly high nitrate but no trace of ammonia or nitrite — keep all three near zero and the disagreement stops mattering. 25-28 °C, soft acidic water, dim light. The sources disagree about plants, which is why this ray does not carry a not-plant-safe flag: Seriously Fish says substrate-rooted plants will be eaten and that even Java fern or Anubias tied to decor may not survive the rays' attention, while Practical Fishkeeping's Heiko Bleher recommends a low Echinodorus lawn for this very species and says they love to glide over it. In practice: open floor matters more than planting, and whatever you do plant, tie it to wood and expect no guarantees. Keep one, a male-female pair or one male with several females - males are rough with each other, and Seriously Fish notes that male P. motoro are among the most violent in the genus when in spawning mood. Tankmates must be large, calm and preferably upper-water: Geophagus, Heros, big characins, arowana. Avoid suckermouth catfish, which rasp at the disc, and anything small enough to be taken at night. A weighted, tight-fitting lid, because rays breach at feeding time. Handle with the assumption that you will be stung if you are careless.

Diet

Carnivore with a fast metabolism, fed two to three times daily. Mussel, cockle, prawn, river shrimp, squid, whitebait and earthworm for adults; bloodworm, Mysis and krill for juveniles. No mammalian meat, no feeder fish. Newly imported fish often need live food before they will take frozen.

Telling males from females

There is no reliable way to sex this species by eye. That is the honest answer, not a gap in our data.

Also in these lists

Similar species

Same category and the closest water parameters — if this species isn't quite it, start here.

Sold in Lithuania

These Lithuanian shops listed this species in their public catalogue (checked August 8, 2026). Stock moves — ask before you travel.

These links are unpaid: we get nothing for them and ask for nothing.

Frequently asked questions

What tank size does a Ocellate River Stingray need?

A Ocellate River Stingray needs an aquarium of at least 1700 litres (449.1 US gallons) with a footprint at least 240 cm (94.5 in) long — for this species, swimming length matters as much as raw volume.

What water parameters does a Ocellate River Stingray need?

Ocellate River Stingray does best at 24–30 °C (75.2–86 °F), pH 5.5–7.5 and a general hardness of 1–12 °dGH.

Is the Ocellate River Stingray suitable for beginners?

Ocellate River Stingray is a demanding species best attempted with some experience — it needs stable, closely watched conditions to thrive.

Sources

• FishBase — Potamotrygon motoro (South American freshwater stingray)
• Seriously Fish — Potamotrygon motoro (Motoro Stingray, P01, P03, P044)
• Maidenhead Aquatics (Fishkeeper) — Motoro Stingray, Potamotrygon motoro
• Journal of Venomous Animals and Toxins including Tropical Diseases — Injuries by marine and freshwater stingrays (Haddad Jr, Cardoso & Garrone Neto, 2013)
• Practical Fishkeeping — Definitive guide to South American freshwater rays (Heiko Bleher)
• IUCN Red List — Potamotrygon motoro (Ocellate Freshwater Stingray)
• Wikipedia — List of species protected by CITES Appendix III
• Wikipedia — CITES (Regulation of trade, Appendix III)
• Aquarium Glaser — Potamotrygon wallacei (trade note on the Appendix III listing)