Pseudobatos horkelii · Rhinobatidae · predator
Brazilian guitarfish of the South Atlantic, from Rio de Janeiro to Argentina. It is critically endangered in Brazil: catching it is prohibited, and the right thing is to recognize it and release it.
Also called: viola, guitarra, Brazilian guitarfish
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 Brazilian guitarfish belongs to the family Rhinobatidae and reaches 138 cm. It lives from the coast to the edge of the continental shelf, 1 to 150 m deep, between Rio de Janeiro and Argentina. It feeds on crustaceans, cephalopods, polychaetes and small fish. It is ovoviviparous: the embryos first feed on the yolk and then on a fluid from the uterus. Each litter has 4 to 12 pups. Females mature at around 90 cm. It is caught in commercial fishing, and in Brazil catching it is prohibited.
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 brazilian guitarfish.
Ray with a uniform back, olive brown or chocolate brown, without light or dark blotches. The snout has an oval dark patch, and the nostrils are longer. The head is flat on top, and the middle row of tubercles is larger and shaped like a spine. The first dorsal fin starts behind the tip of the pelvic fins.
Occurs in the Southwest Atlantic, from Rio de Janeiro to Argentina, passing through Uruguay, on coastal and shelf bottoms.
Habitat: From the coast to the edge of the shelf, on sand and mud bottoms, 1 to 150 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 CR. Global IUCN assessment: CR.
The national list (Portaria GM/MMA nº 1.667/2026) classifies the species as CR. Under Portaria GM/MMA nº 1.666/2026 (art. 3), VU, EN and CR species have full protection: catch, transport, storage, processing and trade are banned. If you hook one by accident, release it right away, with minimal handling.
Source: Portaria GM/MMA nº 1.666/2026, art. 3º, and Portaria GM/MMA nº 1.667/2026
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.
Source: Portaria GM/MMA nº 1.666/2026 (art. 3º) and nº 1.667/2026 (Annex I)
Critically endangered species: capture is prohibited in Brazil. If you hook it by accident, release it right away, with minimal handling.
Length-weight relationship W = a·Lb (a = 0.00282, b = 3.12; FishBase (relação peso-comprimento bayesiana, estimativa pelo gênero e formato do corpo)). 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.
