the right time
to be on the water
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.
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hour by hour
slide your finger or mouse over the chart to see each hoursee hour-by-hour table
why this index at —?
choose the day
the fishing month at a glance
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.
everything about the roudi escolar
how to recognize it
Elongated and moderately compressed body, gray to coppery bronze. The mouth has fang-like teeth, and the mouth and gill cavity are black. Smaller specimens have yellowish fins with black tips, and the first dorsal fin has a black spot at the front. Above 40 cm the fins become almost black and the pelvic fin disappears.
where found
open on the large mapWhere to look: Continental slope and oceanic islands, between 300 and 400 m, rising to midwater at night.
In Latin America it occurs in Brazil, the Caribbean, Colombia, Venezuela and the Guianas, in tropical and subtropical seas.
coast
rules for the roudi escolar
Rules change; before keeping or transporting fish, check with the state environmental agency.
We found no species-specific rule beyond the region's general rules.
Conservation: Not on the Brazilian national list (Ministerial Ordinance GM/MMA No. 1.667/2026).
how much it weighs without taking it out of the water
estimated weight
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how we calculate
Length-weight relationship W = a·Lb (a = 0.00363, b = 3.06; FishBase (relação peso-comprimento bayesiana, estimativa da própria espécie)). It's an average: a fat or lean fish can vary by 10% to 20%.
more about the roudi escolar
The Promethean escolar is a snake mackerel of the family Gempylidae, an elongated fish with a mouth full of fang-like teeth. It reaches 100 cm and lives on the continental slope and seamounts, between 80 and 800 m, usually between 300 and 400 m. At night it rises to midwater. It eats fish, squid and crustaceans. It occurs in tropical and subtropical seas of all oceans, including Brazil and the Caribbean. It is caught in subsistence fishing, and some sport anglers seek it.
Family: Gempylidae · predator
fun facts
- At night it migrates to midwater.
- Eggs and larvae are pelagic, that is, they live in the water column.
in the kitchen
It is caught in subsistence fishing, but there are reports of ciguatera, so the flesh needs care.
similar species
sources and references (3)
Essential profile: size, length-weight, depth, countries and conservation come from FishBase and the cited regulations, and the texts were written from those sources. Season, time of day, sensitivities, technique and baits and lures are not included yet, because we did not find a good source for this species.
- scientific FishBase: Promethichthys prometheus (ficha da espécie)Size, length-weight, depth, habitat, distribution, biology, and IUCN status. Page checked on Oct 13, 2026.
- scientific FishBase: nomes populares de Promethichthys prometheusNames by country and language.
- official Portaria GM/MMA nº 1.667, de 27 de abril de 2026: Lista Nacional Oficial de Espécies da Fauna Ameaçadas de Extinção (peixes e invertebrados aquáticos)The species is not on the list. Checked in the DOU of April 28, 2026.
how we calculatewhere each number comes from
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.
sources for this lookup
how accurate the forecast is
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: