A small shark, found only in the South Atlantic, that eats crabs on the bottom. Critically Endangered in Brazil: catch prohibited. In Argentina, the gatuzo may be kept in mixed fishing, with a minimum size and a quota.
Also called: cação-malhado, cação-cola-fina, cação-canejo, canejo, gatuzo
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…
0—
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
—
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 narrownose smooth-hound
overview
who is the narrownose smooth-hound
The cação-malhado, the gatuzo of Argentines, exists only in the southwestern Atlantic, from southern Brazil to northern Patagonia. It is a small shark, at most 90 cm, that lives near the bottom on the shelf and comes into beaches and bays, where it hunts crabs, other crustaceans and small fish. It has 2 to 7 pups per pregnancy, born at about 26 cm. It is heavily exploited by commercial fishing in the region, and in Brazil it is Critically Endangered, with catch prohibited. In Buenos Aires Province it is a common species in beach and boat 'mixed fishing', with a minimum size and a daily limit.
fun facts
Found only in the southwestern Atlantic, from southern Brazil to Patagonia.
Its low, mosaic-like teeth work like a plate for crushing crabs.
It has 2 to 7 pups per pregnancy, born at about 26 cm.
how to recognize it
identification
A small, slender shark, gray to grayish brown on the back, usually with scattered white spots, pale belly. Short, pointed snout, oval eyes. The two dorsal fins are nearly the same size. Low, mosaic-like teeth for crushing. The cação-bico-doce is larger, without spots, with a much smaller second dorsal fin and a large lobe at the tip of the tail. Other coastal Mustelus (M. canis, EN; M. fasciatus, CR) are also protected.
In Brazil, along the southern coast, especially in Rio Grande do Sul. Endemic to the southwestern Atlantic, from southern Brazil to northern Argentine Patagonia, including Uruguay and the Buenos Aires coast.
Habitat: Sandy and muddy bottoms of the continental shelf, beaches and bays.
coast
South Coastcoastalshelf
states
Santa Catarina, Rio Grande do Sul
calendar and clock
when to fish
best season
time of yearbest: Nov–Jan
JanFebSeaAprMayJunJulAugSepOctNovDec
Estimate: on the Buenos Aires coast the gatuzo comes close to beaches in spring and summer; in southern Brazil it also appears in the cold months. Biological information: in Brazil, catch is prohibited year-round.
best time of day
Any time. Feeds day and night, always on the bottom.
weather, water and behavior
what affects the narrownose smooth-hound
sensitivity The little bars show how much each factor affects this species. Five full: it feels it a lot.
cold and cold fronts
A temperate-water species; tolerates cold water.
atmospheric pressure
Cold fronts bring rough seas.
moon
Little known effect.
rain
Not very relevant.
water level
Not applicable at sea.
noise
Not very sensitive.
wind
Rough seas prevent beach fishing.
tide
A rising tide brings crabs and small fish to the shore.
beach: 12' to 14' for a 100 to 150 g sinker; boat: 6' to 7', 15 to 30 lb
spinning / baitcasting reel
5000 to 7000 spinning reel
line
monofilament 0.35 to 0.45 mm
leader
0.60 mm monofilament, up to 3 single hooks per rod (mixed-fishing rule in Buenos Aires)
hook
circle hook 2/0 to 4/0
natural baits
shrimp
lula
fish fillet
caranguejo
accessories
alicate
desanzolador
measuring ruler (60 cm minimum in Buenos Aires)
tip from an angler
In Brazil catch is prohibited: release it in the water. In Argentina, measure before keeping it and respect the limit of 10 per day; those under 60 cm go back to the sea.
what the law says
rules for the narrownose smooth-hound
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: Catch prohibited throughout Brazil. Global: Critically Endangered (IUCN, July 1, 2019).
Threatened species (CR): catch prohibited in Brazil
catching, transport, holding and trade prohibited
The cação-malhado (Mustelus schmitti) is on the national list as Critically Endangered (CR) (it was already on the previous list, Portaria MMA 148/2022). Ministerial Ordinance GM/MMA 1.666/2026 (art. 3) prohibits catch, transport, storage, possession, processing and trade throughout Brazil. Anyone who hooks one by chance must release it alive immediately (art. 3, § 4). The rule does not authorize targeted fishing, even with release: in Brazil, do not seek this species.
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.
Buenos Aires (AR): gatuzo, 60 cm minimum size and up to 10 per day
60 cm minimum size; up to 10 killed per angler per day
In Buenos Aires Province marine sport fishing, the gatuzo is part of the 'mixed fishing' category. Minimum catch size of 60 cm; each angler may keep a maximum of 10 gatuzos per day, within the total of 40 pieces of mixed fishing; beyond that, release is mandatory. Maximum of three single hooks per rod. In Río Negro, Law 5.706/2023 allows the gatuzo to be added to mandatory release by resolution of the fishing authority (art. 22).
North CoastNortheast CoastSoutheast CoastSouth Coast
Many sharks and rays are on the national list (CR, EN or VU), with catching, keeping and transport prohibited, including those listed here. Species added to the list only in 2026 follow the 180-day deadline (until about Oct 25, 2026). If unsure of the species, release it.
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.
Remove the hook with a dehooker while it is still in the water or with the fish wet, holding it by the body, and release it right away. It is small and handles quick release well.
in the kitchen
Catch and trade prohibited in Brazil. In Argentina it is eaten, within the minimum size and quota.
calculator
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.00263, b = 3.1; FishBase (estimativa bayesiana para a espécie e o gênero, comprimento total)). It's an average: a fat or lean fish can vary by 10% to 20%.
estimated weight
—
sources and references
The seasonal weights (months), time of day and sensitivities (cold, pressure, moon, wind, rain, tide, bright 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 show when an 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 norm and link. The maximum weight (about 3.2 kg) was calculated from FishBase's length-weight relationship for the maximum length of 92 cm, because no maximum weight is published.
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.
