SeaEstuaryFreshwaternational list: VU · vulnerable
A robust, short-snouted shark that enters estuaries and swims up rivers. Vulnerable on the 2026 national list: catch prohibited in Brazil from late October 2026.
Also called: tubarão-cabeça-chata, cabeça-chata, cação-cabeça-chata, tubarão-touro, tubarão-buldogue, sicuri-branco
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.
location
Sample location: choose yours to see the forecast for where you fish.
period
Reading the weather across 3 global models and 31 simulations…
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index Score from 0 to 100 for the fishing conditions of each hour. It reads weather, sun, moon, tide and the species' habits. It doesn't promise fish: it tells you when the water is on your side. 0–24 poor · 25–44 fair · 45–64 good · 65–84 very good · 85–100 excellent.
today
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confidence —
confidence How much you can trust the weather forecast for the day. It drops with distance and when the models disagree. It is not the chance of catching fish.
models and trend Up to 16 days, three global weather models (the European ECMWF, the American GFS and a high-resolution blend) read hour by hour; when they disagree, the light band on the chart widens. Beyond that it's a trend: 31 runs of the American GEFS model. Confirm when it's 1 week out.
window Consecutive hours with the index near the day's peak and no danger alert. It is the time to have the bait in the water.
hour by hour
tap or drag on the chart to read each hour · on a keyboard, arrow keys
see hour-by-hour table
why this index at —?
next 7 days
choose the day
chart: bar height = day's index · line = variation between models · striped = trend · fainter = less confidence
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.
4-week calendar
the fishing month at a glance
plan a trip
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.
the species
everything about the bull shark
overview
who is the bull shark
The bull shark lives in warm, shallow waters worldwide: beaches, bays, estuaries, mangroves and ports. It is one of the few sharks that tolerate fresh water for long periods, and it has been recorded in the Amazon River, Lake Nicaragua and African rivers. Robust and territorial, it eats fish, rays, other sharks, turtles and whatever it finds in murky water. In Brazil it occurs along the whole coast, more in the North and Northeast. Because it lives so close to shore, it is heavily caught in nets and lines, and the 2026 national list classified it as Vulnerable. In several Caribbean and Central American countries it is sought in catch-and-release sport fishing at river mouths and lagoons.
fun facts
It regulates the salt in its body and can live for months in fresh water; it has been found thousands of kilometers from the mouth of the Amazon.
In Nicaraguan rivers, it swims up the San Juan River to Lake Nicaragua.
In a catch-and-release study in the US and the Bahamas, it built up less lactic acid than the hammerhead and the blacktip.
how to recognize it
identification
Very thick, heavy body, plain gray on the back and white on the belly, without strong markings. Very short, broad, rounded snout, small eyes. Large, triangular first dorsal fin, relatively tall second dorsal fin, no ridge between the dorsals. The tiger shark also has a short snout, but it has stripes and a longer tail; the lemon shark has two dorsals of nearly the same size and a yellowish color; the bronze whaler has a longer, pointed snout.
The entire Brazilian coast, more common in the North and Northeast; enters estuaries and has been recorded in the Amazon River. In the western Atlantic it ranges from the United States to Argentina; in the Pacific, from Mexico to Ecuador. Famous in Lake Nicaragua and the San Juan River (Nicaragua and Costa Rica).
Habitat: Beaches, bays, mangroves, estuaries, river mouths, ports and coastal lagoons; swims up rivers.
coast
North CoastNortheast CoastSoutheast CoastSouth Coastcoastalshelf
states
Amapá, Pará, Maranhão, Piauí, Ceará, Rio Grande do Norte, Paraíba, Pernambuco, Alagoas, Sergipe, Bahia, Espírito Santo, Rio de Janeiro, São Paulo, Paraná, Santa Catarina, Rio Grande do Sul
calendar and clock
when to fish
best season
time of year
JanFebSeaAprMayJunJulAugSepOctNovDec
Estimate: present year-round in the North and Northeast; closer to shore in warm months. Biological information: in Brazil, catch is prohibited from late October 2026.
best time of day
Night and twilight. Hunts mostly at night and at dusk, in murky water; by day it stays in channels and holes.
weather, water and behavior
what affects the bull shark
sensitivity The little bars show how much each factor affects this species. Five full: it feels it a lot.
cold and cold fronts
A warm-water species; avoids cold water.
atmospheric pressure
Not very relevant.
moon
New and full moon tides move prey at estuary mouths.
rain
Rain and muddy water don't bother it: it's a hunter of murky water.
water level
A high river carries the bull shark into the estuaries.
noise
Not very sensitive; often comes close to boats and piers.
wind
Not very significant inside estuaries.
tide
A flood tide carries the shark into the bar mouths and channels; an ebb tide concentrates prey at the mouths.
lever-drag baitcaster 30 or 14000 spinning reel with strong drag
line
braided line 80 to 100 lb
leader
1.5 to 2 m wire leader plus 2 to 3 m of 200 lb monofilament
hook
circle hook 12/0 to 16/0, barbless; single hook only
natural baits
cut bait or whole fish (mullet, catfish, jack) on the bottom, where fishing is permitted
accessories
cutting pliers for steel cable
long hook remover
luvas
tip from an angler
In Brazil, from late October 2026, only release of incidental catch. Where catch and release is allowed, use a circle hook, keep the fight short and release it in the water. The bull shark is one of the most dangerous sharks alongside the boat: never put your hands near its mouth.
what the law says
rules for the bull shark
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: New species on the 2026 list: the bans apply from late October 2026. Global: Vulnerable (IUCN, November 24, 2020). Listed in CITES Appendix II.
Threatened species (VU): catch prohibited in Brazil
catch, transport, possession and trade prohibited (from late October 2026)
The bull shark (Carcharhinus leucas) entered Brazil's national list in 2026 as Vulnerable (VU). Ministerial Ordinance GM/MMA 1.666/2026 (art. 3) gives full protection to VU, EN and CR species: catch, transport, storage, possession, processing and trade are prohibited. For species not on the previous list, a 180-day transition period applies from publication (April 28, 2026), so the ban takes effect from late October 2026 onward (around October 25; Fiperj, Rio de Janeiro's fisheries agency, gives October 27, 2026). Anyone who hooks one by chance must release it alive immediately (art. 3, § 4). The rule does not authorize targeted fishing, even with release.
Finning prohibited: shark only whole, with its fins
fins naturally attached to the body
In Brazil, finning is prohibited (cutting off the fins and discarding the body). Every shark or ray landed must arrive with its fins attached to the body; it is prohibited to carry on board an animal without fins or with loose fins, and to transfer sharks between vessels. It applies to any shark that may be kept.
1 specimen per angler per day (counts as 5 against the quota of 10)
In recreational sport fishing in Mexican saltwaters, the limit for sharks is one specimen per angler per day, which counts as five toward the total limit of ten fish. Fish caught in sport fishing may not be sold. Catch and release does not count toward the limit: prefer releasing.
commercial or sport extraction not permittedconfirm with the agency
In 2021 Colombia stopped considering sharks and marine rays a fishery resource and began treating them as a hydrobiological resource; the recitals of Decree 281/2021 state that they may not be extracted for commercial or sport purposes, and the decree created an environmental protection plan. Later AUNAP rules dealt with incidental catch in artisanal fishing; we did not check the consolidated text. When in doubt, release it into the water.
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.
Keep the shark in the water; on a beach or a bank, don't drag it across the sand. Cut the leader close to the mouth if the hook is deep. Revive it facing the current until it swims off strongly.
in the kitchen
Catch prohibited in Brazil from late October 2026. Large sharks accumulate mercury. Don't buy "cação" (shark meat) of unknown origin.
calculator
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.00501, b = 3.06; FishBase (estimativa bayesiana para a espécie, comprimento total)). It's an average: a fat or lean fish can vary by 10% to 20%.
estimated weight
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sources and references
The seasonal weights (months), time of day and sensitivities (cold, pressure, moon, wind, rain, tide, strong light, murky water and noise) are the app's editorial estimates, based on the literature below and on field experience of anglers and guides. The months indicate the time of year when the angler usually finds the species near the coast, not a catch season. They are not official data or measurements made for this species and may vary by region and year. Legal rules appear in the rules section, with the regulation and link.
officialPortaria GM/MMA nº 1.666, de 27 de abril de 2026 — regras de proteção das espécies ameaçadas da lista nacionalArt. 3: full protection for VU, EN and CR species; § 4: incidental catch with immediate release of the live animal. The 180-day transition rule for species newly added to the list was verified from official summaries (Fiperj) and technical sources; the DOU (Brazil's Official Gazette) page did not open during verification.
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:
where are you going fishing?
Your location is saved only on this device and feeds the forecast, the map and the "today" on the home page.
