The most widespread freshwater stingray in South America, with yellow-orange ocelli on its back. The tail spine causes intense pain and wounds that take a long time to heal.
Also called: arraia, arraia-de-água-doce, raia, raia-motoro, boró, arraia-grande, arraia-de-fogo, arraia-maçã
Choose the place and the species. The index, from 0 to 100, combines weather, sun, moon and tide with each fish's habits. Up to 28 days, with each day's confidence.
location
Sample location: choose yours to see the forecast for where you fish.
period
Reading the weather across 3 global models and 31 simulations…
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index Score from 0 to 100 for the fishing conditions of each hour. It reads weather, sun, moon, tide and the species' habits. It doesn't promise fish: it tells you when the water is on your side. 0–24 poor · 25–44 fair · 45–64 good · 65–84 very good · 85–100 excellent.
today
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confidence —
confidence How much you can trust the weather forecast for the day. It drops with distance and when the models disagree. It is not the chance of catching fish.
models and trend Up to 16 days, three global weather models (the European ECMWF, the American GFS and a high-resolution blend) read hour by hour; when they disagree, the light band on the chart widens. Beyond that it's a trend: 31 runs of the American GEFS model. Confirm when it's 1 week out.
window Consecutive hours with the index near the day's peak and no danger alert. It is the time to have the bait in the water.
hour by hour
slide your finger or mouse over the chart to see each hour
see hour-by-hour table
why this index at —?
next 7 days
choose the day
chart: bar height = day's index · line = variation between models · striped = trend · fainter = less confidence
Each card shows the day's index (0 to 100) and, below it, a strip with the index for each hour, from 0h to 23h. from poor to excellent.
4-week calendar
the fishing month at a glance
plan a trip
what's the best window for the crew?
Choose how many fishing days. We compare each stretch by its average index, discount days with a warning or closed season, and show the 3 best.
trend for the coming weeks
Line: the middle value of 31 simulations of the American GEFS model. Band: where 8 out of 10 fall. Narrow, firm trend; wide, high uncertainty.
the species
everything about the ocellate river stingray
overview
who is the ocellate river stingray
Freshwater stingray with an almost round disc that buries itself in the sand or mud of beaches, banks and lagoons, feeding on invertebrates and small fish. Found in the Amazon, Orinoco, Paraguay-Paraná and Uruguay basins. In the upper Paraná, there were no stingrays until the Sete Quedas barrier was submerged by the Itaipu reservoir; since then, species from the middle Paraná moved upriver and now appear in the upper Paraná and in tributaries such as the Paranaíba. Accidents affect swimmers and fishers who step on the fish in shallow water or handle it after hooking it. The serrated tail spine injects venom: the pain is intense and the skin around the wound often necroses. In the Plata basin there are other similar ocellated stingrays, two of them described in 2013.
fun facts
The spine is a modified scale (a skin denticle), serrated, that falls off and is replaced from time to time; some stingrays have two.
Freshwater stingrays give birth to fully formed young, few per pregnancy.
how to recognize it
identification
Rounded disc, olive-brown to grey on the back, covered in ocelli (round spots) yellow to orange with dark edges, eye-sized or larger and evenly spread. Belly with a large whitish central area and grey edges. Short, thick tail with one or two serrated spines. The names arraia-de-fogo and arraia-maçã are also used for Paratrygon aiereba, which has a wider disc and a thin, short tail, is Critically Endangered and may not be caught.
Amazon and Orinoco basins, Paraguay-Paraná system and Uruguay basin. In the upper Paraná (SP, PR, MS, MG and GO), stingrays arrived after the Itaipu reservoir formed in 1982, and Paraná and Goiás treat the stingrays of that basin as non-native.
Habitat: Sand and mud bottom on beaches, shallow banks, eddies, lagoons and lake mouths; it lies buried, with only its eyes showing.
Amazonas, Pará, Amapá, Roraima, Rondônia, Acre, Mato Grosso, Tocantins, Mato Grosso do Sul, Goiás, São Paulo, Paraná, Minas Gerais, Rio Grande do Sul
calendar and clock
when to fish
best season
time of yearbest: Jul–Oct
JanFebSeaAprMayJunJulAugSepOctNovDec
Not a target species. In the dry season, with beaches and shallow banks, accidents are more common: shuffle your feet when entering the water.
best time of day
Night and twilight. Hunts more at night and at dusk; by day it usually stays buried in the shallows.
weather, water and behavior
what affects the ocellate river stingray
sensitivity The little bars show how much each factor affects this species. Five full: it feels it a lot.
cold and cold fronts
Cold water keeps the stingray still and buried, even harder to spot.
atmospheric pressure
Little known effect.
moon
Little known effect.
rain
Murky water hides stingrays in the shallows: take extra care.
water level
Low water exposes beaches and sandbars, where stingrays lie.
noise
Not very sensitive; usually stays still and does not flee.
wind
Little effect.
depth
Shallow, 0.2 to 2 m on the beaches; deeper in the channel.
technique, gear and bait
how to fish
rod
not applicable: not a target species
spinning / baitcasting reel
not applicable
line
not applicable
leader
not applicable
hook
not applicable
accessories
long-handled pliers
knife or scissors to cut the line
closed shoes or water boots
tip from an angler
Hooked a stingray? Don't bring it into the boat and don't step on it on the bank. Keep the tail away from your legs and cut the line near the mouth with long-handled pliers. In Paraná, check the state rule.
what the law says
rules for the ocellate river stingray
Summary of the regulations we found, with the source for each. Rules change; before keeping or transporting fish, check with the state environmental agency. Conservation: Not on the national list (Portaria GM/MMA nº 1.667/2026), which includes other freshwater stingrays, such as Paratrygon aiereba (CR), Potamotrygon leopoldi (VU), P. marquesi (VU) and P. signata (EN). In Colombia, the Libro Rojo (2012) lists the motoro stingray as Vulnerable (VU).
PR: stingrays are non-native in the inland basins
catch allowed with no minimum size; the rule forbids releasing non-native fishPRParanáSoutheast Atlantic
In Paraná, stingrays (Potamotrygon spp.) are on the list of non-native fish with permitted catch, exempt from size rules, and the same ordinance bans releasing captured non-native fish. Never hold a stingray with your hands or bring it close to your body: the spine stays dangerous out of the water.
piracema closures in the basins where the species lives
Closed season in Goiás (state rule)
01/11 to 28/02GO
Allowed: Sport and guided fishing only in reservoirs, catch and release with barbless hooks (no keeping, transporting or eating). Subsistence: up to 5 kg per day, for household consumption only.
Spawning closure (piracema) in the Pantanal of Mato Grosso do Sul
05/11 to 28/02MS
Allowed: Subsistence fishing by riverside residents and authorized scientific fishing. Decree 15.166/2019 (art. 11, §5) allows catch and release only in February and only in the channels of the Paraguay and Paraná rivers. For the rest of the period, not even catch and release is allowed. Check the Imasul portaria for each season.
Spawning closure (piracema) in Mato Grosso (all basins)
01/10 to 31/01MT
Allowed: All fishing modalities are prohibited in rivers, including catch and release (Law 9.096/2009, art. 19-A). Exceptions: subsistence fishing from shore (3 kg or 1 fish, no transport or sale) and scientific fishing. Law 13.159/2025 now allows licensed sport fishing in UHE/PCH hydropower reservoirs, natural lakes and border rivers, subject to a scientific study and a license from the environmental agency. We have not confirmed whether these licenses are already being issued.
Spawning closure (piracema) in the Araguaia River basin
01/11 to 28/02GOTOPAMT
Allowed: Recreational fishing only in reservoirs, with handline, rod, or spinning or baitcasting reel. Fish may only be eaten on site, not transported. Competitions prohibited. Subsistence: 3 kg + 1 fish. State rules (GO and TO) may be stricter.
Spawning closure (piracema) in Tocantins (state rule)
01/11 to 28/02TO
Allowed: In 2025/26: catch and release with barbless hooks and recreational fishing card; subsistence fishing on foot or from a rowboat, with simple pole or handline.
Spawning closure (piracema) in the Uruguay River basin
01/10 to 31/01RSSC
Allowed: Recreational fishing from shore, or from a boat without motor. Only handline or rod, line and hook, one gear per angler, up to 5 kg. Prohibited in floodplain lakes, within 1,500 m of dams, within 500 m of confluences, and in stretches listed in the rule (e.g., Turvo River).
Allowed: Recreational anglers with handline or rod, line and hook are outside the Annex II prohibitions, with a bag limit of 5 kg + 1 fish, unless a stricter state rule applies.
catch and release Releasing the fish alive, quickly and with a wet hand. During a closed season it isn't always allowed: what the regulation says applies.
Do not hold it by the tail or the disc. With the stingray in the water, cut the line near its mouth with long-handled pliers. Sting: wash the area with water, then immerse it in hot water, as hot as the person can bear without burning (test on someone else's hand), until the pain eases, and get medical care: the wound often necroses and can become infected. Do not apply a tourniquet, cut, or suck at the wound.
in the kitchen
Rarely eaten. When cleaning a dead stingray, remember the spine is still dangerous.
calculator
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.01, b = 3.04; FishBase). It's an average: a fat or lean fish can vary by 10% to 20%.
estimated weight
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sources and references
The season weights (months), the time of day and the sensitivities (cold, pressure, moon, wind, rain, tide, strong light, murky water and noise) are the app's editorial estimates, based on the literature below and on the field experience of anglers and guides. They are not official data nor a measurement made for this species, and they may vary by region and year. Closed seasons and legal rules appear in the rules section, with the norm and a link.
scientificFishBase — Potamotrygon motoro (ficha da espécie)Distribution, size (up to 50 cm disc width, 100 cm total length and a published maximum weight of 34.2 kg), threat to people (traumatogenic) and country list. Page checked on Oct 13, 2026.
The weather comes from three independent global models, cross-checked hour by hour: when they agree, confidence goes up; when they diverge, the band between them shows on the chart. Beyond 16 days, we use the GEFS ensemble of 31 simulations: if 20 of the 31 predict rain, the chance of rain is 65%. Sun and moon are calculated astronomically, with no uncertainty.
The index adds up, weighted for each species: time of day (species curve anchored to real sunrise and sunset), moon (transits, rise and set, phase), pressure (3 h trend and 24 h swing), water temperature (in rivers, estimated from air temperature; at sea, estimated by an ocean model), wind, rain, clouds, tide and the month in the species' cycle.
Accuracy measured in the reference project (4 regions, 93 days, forecast vs. observed): maximum temperature is off by 0.6 °C on average the next day and 1.7 °C at 7 days; rain of 5 mm or more is detected 76% of the time the next day and 57% at 7 days. Detection isn't everything: the false alarm rate isn't published here yet, and 93 days in 4 regions is still a small sample. We now also measure every day, at the app's destinations:
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Your location is saved only on this device and feeds the forecast, the map and the "today" on the home page.
