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 black grunt
how to recognize it
Silvery blue, with many oblique dark yellow stripes along the body. It has a small amount of black pigment under the upper edge of the preopercle, the cheek bone behind the eye. Spindle-shaped body, normal for grunts. The pattern of oblique stripes on the body is what separates this species from the other grunts in the region.
Also called: roncador-de-listras-oblíquas, ronco prieto, ronco rayado, corocoro rayado, black grunt
don't confuse with:
We don't have tips on season, bait or technique for this species yet.
where found
open on the large mapWhere to look: Shallow shelf areas, on mud and sand bottoms, 1 to 50 m deep.
Western Atlantic, from southern Florida and the Antilles to Venezuela, in the Caribbean, the Gulf of Mexico and the coast of Central America. Uruguay also appears among the countries of occurrence.
rules for the black grunt
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.
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 = 0.0166, b = 2.95; 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 black grunt
Fish of the family Haemulidae, reaching 40 cm. It occurs in the western Atlantic, from southern Florida and the Antilles to Venezuela; Uruguay also appears among the countries of occurrence. It lives in shallow shelf areas, on mud and mud-sand bottoms, from 1 to 50 m deep, and is less common in clear waters with coral reefs. It has commercial use and is sold fresh and salted. There are reports of ciguatera in this species.
Family: Haemulidae · predator
in the kitchen
Sold fresh and salted. There are reports of ciguatera, so avoid eating specimens of doubtful origin.
similar species
sources and references (2)
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: Haemulon bonariense (ficha da espécie)Size, length-weight, depth, habitat, distribution, biology, and IUCN status. Page checked on Oct 13, 2026.
- scientific FishBase: nomes populares de Haemulon bonarienseNames by country and language.
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: