Rhincodon typus · Rhincodontidae · forage fish
The largest fish in the world, which filters plankton near the surface. It is threatened in Brazil, and catching it is prohibited: the right thing is to recognize it and release it.
Also called: tubarão-baleia, tiburón ballena, pez dama, whale shark
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…
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.
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.
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.
The whale shark belongs to the family Rhincodontidae and reaches 1,700 cm. It is the largest fish in the world and poses no danger to people. It lives in open ocean, but often appears near the coast, in lagoons and coral atolls and, sometimes, in shallow waters of estuaries and river mouths, during periods of shrimp abundance. It is usually seen alone or in groups of more than 100 individuals, often together with schools of pelagic fish. It feeds on plankton and small fish, crustaceans and squid, filtering water through its modified gills. It is ovoviviparous, with litters of more than 300 pups. It migrates between ocean basins and returns to the same places every year.
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 whale shark.
Huge shark with a broad, flattened head and a large mouth, almost in front of the eyes. The back is grey, bluish or greenish brown, with white or yellow spots and stripes in a checkerboard pattern. The underside is white or yellowish. It has skin ridges along the body that end in a keel on the tail stock, and spiracles near the eyes, larger than the eyes themselves.
Occurs in tropical and subtropical seas across almost all of Latin America, in the Atlantic and the Pacific, mainly in open ocean and near the coast.
Habitat: Open ocean and coastal waters, near the surface, from 0 to 100 m deep.
coast
Summary of the regulations we found, with the source for each. Rules change; before keeping or transporting fish, check with the state environmental agency.
Conservation: On the national list of threatened species as VU. Global IUCN assessment: EN.
The national list (Portaria GM/MMA nº 1.667/2026) classifies the species as VU. Under Portaria GM/MMA nº 1.666/2026 (art. 3º), VU, EN and CR species have full protection: catch, transport, storage, processing and sale are banned. If you hook one by accident, release it at once, handling it as little as possible.
Source: Portaria GM/MMA nº 1.666/2026, art. 3º, and Portaria GM/MMA nº 1.667/2026
Threatened species: catching it is prohibited in Brazil. If you hook one by accident, release it right away, with minimal handling.
Length-weight relationship W = a·Lb (a = 0.00389, b = 3.12; FishBase (relação peso-comprimento bayesiana, estimativa)). It's an average: a fat or lean fish can vary by 10% to 20%.
estimated weight
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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.
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.
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:
Your location is saved only on this device and feeds the forecast, the map and the "today" on the home page.
