Odontesthes argentinensis · Atherinopsidae · omnivore
The silverside of the beaches, jetties and estuaries of the South, a marine cousin of the lake pejerrey. It travels in schools and is caught on float with small baits, especially in the cold.
Also called: peixe-rei-do-mar, peixe-rei, mamarreis
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.
Reading the weather across 3 global models and 31 simulations…
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.
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.
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 peixe-rei-do-mar is an atherinopsid, the silverside family, from the coastal strip of southern Brazil, Uruguay and Argentina. It occupies beaches, jetties, bays and the mouths of estuaries and coastal lagoons, and enters brackish water; it is common in the Patos Lagoon estuary. It grows past 40 cm, but the usual size is 20 to 30 cm. It eats small crustaceans, larvae and tiny fish. It is the silverside of the jetties of Rio Grande do Sul and of the piers of Uruguay and Buenos Aires, caught on float with small baits. It is not the same as the freshwater pejerrey (Odontesthes bonariensis), of lakes and rivers, which has its own entry.
Elongated, slender body, greenish to bluish back and silvery flanks, with a broad silver band along the flank. Two small, separate dorsal fins (the first with 6 fine spines), long anal fin and small mouth. Telling it apart from the freshwater silverside by appearance is hard: habitat helps, but in estuaries the two species can mix, and a reliable separation requires counting scales and rays. The sand silverside (Atherinella brasiliensis), from the beaches, is smaller.
From the São Paulo coast to Rio Grande do Sul, most common in Santa Catarina and Rio Grande do Sul, including the Patos Lagoon estuary. Outside Brazil, Uruguay and Argentina as far as northern Patagonia.
Habitat: Beaches, surf zone, jetties, bays and mouths of estuaries and coastal lagoons, in salt and brackish water.
coast
states
São Paulo, Paraná, Santa Catarina, Rio Grande do Sul
It is a cold-water fish: at the jetties and beaches of Rio Grande do Sul, Uruguay and Buenos Aires, the peak season runs from autumn to late winter.
Daytime. Active by day, in schools near the surface and in midwater; morning and late afternoon usually produce more at the jetties.
It tolerates cold water well; winter is exactly when it comes closest to shore.
Right after the cold front, as the wind dies down, the schools return to the jetties.
Little effect.
Heavy rain that muddies the water at the inlet scatters the schools.
At the mouths of lagoons and estuaries, it follows the incoming salt water.
Moderate: shallow schools flee noise and shadows on the water.
Strong crosswind makes it hard to control the float and the fine line.
Tide and current moving through the inlet bring food and schools.
0.5 to 4 m; adjust the float until you find the school.
lures
natural baits
accessories
Adjust the float depth until you find the school, almost always in midwater; small bait and fine line make the difference.
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 assessed by the IUCN, according to FishBase. Not on the national list (Portaria GM/MMA 1.667/2026); ICMBio published a national assessment in 2026.
IN MMA 53/2005 sets 10 cm for 'peixe-rei' on the coast from ES to RS, citing Odontesthes bonariensis and Atherinella brasiliensis. The peixe-rei-do-mar (O. argentinensis) is not named: use 10 cm as the minimum reference and confirm with the competent agency.
On the sea coast of Buenos Aires province, pejerreyes fall under "directed fishing", with a limit of 40 fish per angler per day (other species in that category have a limit of 10). A line may have up to five single hooks, or the "lengüe", a rig of up to 15 hooks with artificial lures. We have not confirmed whether the rule remains unchanged.
A delicate fish that loses scales easily: wet your hand, remove the hook quickly and release without squeezing.
White, fine, delicate flesh; a classic fried whole or as breaded fillets in Uruguay and Argentina.
Length-weight relationship W = a·Lb (a = 0.00513, b = 3.06; FishBase (estimativa bayesiana com dados da espécie e do gênero, comprimento total); peso máximo calculado por esta relação). It's an average: a fat or lean fish can vary by 10% to 20%.
estimated weight
—
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.
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:
Your location is saved only on this device and feeds the forecast, the map and the "today" on the home page.
