pacific thread herring
Opisthonema libertate · Dorosomatidae · forage fish
A schooling sardine of the eastern Pacific, the most abundant of its genus in the region. It goes mainly to fishmeal and fish oil, and is sometimes used as bait.
Also called: sardinha-de-fio-do-pacífico, machete de hebra, pinchagua, sardina crinuda, pacific thread herring
- maximum
- 30 cm
- record/max.
- 0.3 kg
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 pacific thread herring
who is the pacific thread herring
A sardine of the family Dorosomatidae, with an elongated, compressed body and a long filament at the end of the dorsal fin, a trait of the genus. It reaches 30 cm and 261 g, and its common size is 22 cm without the tail. It forms dense schools near the surface, in coastal and shelf waters, mostly down to 50 m. It eats phytoplankton, such as dinoflagellates and diatoms, and lays eggs that drift in the plankton. It has great commercial value, mainly for fishmeal and fish oil. It occurs in the eastern Pacific, from Mexico to Peru, with a record also from Chile.
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 pacific thread herring; in the meantime, see the similar species.
identification
Elongated, compressed sardine with a long filament at the end of the dorsal fin, a trait that sets the genus Opisthonema apart from any other sardine of the eastern Pacific. Among the three thread herrings of the region, which look very alike, the safe separation is by gill rakers, which are more numerous in this species. The middle thread herring (Opisthonema medirastre) has a dark spot behind the gill slit and a yellow band on the flank.
where found
Eastern Pacific of Latin America, from Mexico to Peru, with a record also from Chile, in coastal and shelf waters.
Habitat: Coastal and shelf waters, in schools near the surface, mostly down to 50 m.
rules for the pacific thread herring
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.
Harmless. It is a schooling fish with delicate skin and scales: handle it with a wet hand, and keep in mind that most of the catch goes to industry.
in the kitchen
It can be canned, but most goes to fishmeal and fish oil.
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.00676, 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%.
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: Opisthonema libertate (ficha da espécie)Size, length-weight, depth, habitat, distribution, biology, and IUCN status. Page checked on Oct 13, 2026.
- scientific FishBase: nomes populares de Opisthonema libertateNames 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: