shortfin scad
Decapterus macrosoma · Carangidae · forage fish
Small schooling scad, blue-metallic on the back, which feeds on small invertebrates and zooplankton. It is widely used as bait.
Also called: carapau-de-nadadeira-curta, macarela alicorta, jurel fino, shortfin scad
- maximum
- 35 cm
- depth
- 30–70 m
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.
Reading the weather across 3 global models and 31 simulations…
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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
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.
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 shortfin scad
who is the shortfin scad
The shortfin mackerel scad is of the family Carangidae, with a slender body, elongated and nearly round in cross section. It reaches 35 cm, and its common size is 25 cm. It forms pelagic schools and appears on reef slopes near deep water, mostly between 30 and 70 m, within a range of 20 to 214 m. It feeds mainly on small invertebrates and zooplankton. It occurs in several oceans and, in the eastern Pacific, from the Gulf of California to Peru. It is fished commercially, used mainly as bait, and also sold fresh, salted or dried.
Essential profile. Identification, where it occurs and rules, with data from FishBase and the cited regulations. Season, time of day, technique and bait are added once we have a good source for the shortfin scad; in the meantime, see the similar species.
identification
Slender body, elongated and nearly round in cross section, blue-metallic on the back and silvery on the belly, with translucent fins. It has a small black spot on the gill cover, and the dorsal and anal fins are followed by a small detached fin. The scutes along the body are numerous. It is much more slender than other scads and jacks of similar shape, and that helps tell it apart.
where found
Eastern Pacific of Latin America, from the Gulf of California, in Mexico, to Peru, on reef slopes and coastal waters; the species also occurs in other oceans.
Habitat: Reef slopes near deep water, mostly between 30 and 70 m, in pelagic schools.
rules for the shortfin scad
Summary of the regulations we found, with the source for each. 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.
catch and release
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.
No danger to anglers has been recorded. If you are not going to use it as bait, release the fish carefully.
in the kitchen
It is often sold fresh, salted or dried, but it is mainly used as bait.
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.00977, b = 2.97; FishBase (relação peso-comprimento bayesiana, estimativa da própria espécie)). It's an average: a fat or lean fish can vary by 10% to 20%.
estimated weight
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sources and references
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: Decapterus macrosoma (ficha da espécie)Size, length-weight, depth, habitat, distribution, biology, and IUCN status. Page checked on Oct 13, 2026.
- scientific FishBase: nomes populares de Decapterus macrosomaNames by country and language.
similar species
where 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: