american gizzard shad
Dorosoma cepedianum · Dorosomatidae · omnivore
Sardine of large rivers, lakes and estuaries, native to Mexico and introduced to Puerto Rico, where it is exotic. It is mostly used as bait, and is sometimes caught on line.
Also called: sardinha-moela, sardina molleja, sábalo molleja, american gizzard shad, gizzard shad
- maximum
- 57 cm
- record/max.
- 2.0 kg
- depth
- 0–33 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 american gizzard shad
who is the american gizzard shad
Sardine of the family Dorosomatidae, with a deep, silvery body and bluish back. Adults live mostly in fresh water, in large rivers, lakes and reservoirs, but also enter estuaries and brackish bays. It reaches 57 cm and 2 kg, and the common size is about 35 cm. They are filter-feeding herbivores. It spawns near the surface, in fresh water, from mid-March to at least mid-August, in North America. In Mexico it is native. In Puerto Rico it was introduced and is exotic.
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 american gizzard shad; in the meantime, see the similar species.
fun facts
- The eggs are adhesive and sink after being released into the water.
identification
Deep silvery body, with a bluish back and a dark spot just behind the gill opening. The stomach has a thick wall, like a gizzard, which gives the name. The last dorsal-fin ray is long, nearly as long as the distance from snout to pectoral-fin base. Scales are small and irregular, and the mouth is small.
where found
In Latin America, it is native to Mexico, where it lives in rivers, lakes and estuaries, and it was introduced to Puerto Rico, where it is exotic.
Habitat: Large rivers, lakes, reservoirs and brackish estuaries, from 0 to 33 m.
rules for the american gizzard shad
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 the angler. It is mostly used as bait; if returned, release it promptly. In Puerto Rico it is exotic, and it should not be taken to other places.
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.00871, 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: Dorosoma cepedianum (ficha da espécie)Size, length-weight, depth, habitat, distribution, biology, and IUCN status. Page checked on Oct 13, 2026.
- scientific FishBase: nomes populares de Dorosoma cepedianumNames 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: