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.
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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
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 san francisco piranha
how to recognize it
Tall, sturdy body, greenish-grey back and silvery flank with golden reflections; belly, throat and lower fins yellow-orange. Short, blunt snout, projecting lower jaw and sharp triangular teeth. The São Francisco pirambeba (Serrasalmus brandtii) is smaller, flatter and has a more pointed snout.
Also called: piranha, piranha-amarela, piranha-caju, piranha-rodoleira, chupita
don't confuse with:
where found
open on the large mapWhere to look: Eddies, oxbow lagoons, reservoir shores and submerged timber; schools in mid-water.
Native to the São Francisco basin, including the large reservoirs. Also recorded in the Contas River (BA), the Jaguaribe (CE) and, as an allochthonous species, in the Paranaíba in Goiás.
native to the basins
introduced in
states
Minas Gerais, Bahia, Pernambuco, Alagoas, Sergipe, Ceará, Goiás
when to fish
best season
Active in the warm months, September to March; slows down in the depths of winter.
best time of day
Daytime, with peaks at dawn and dusk. Active by day, with more attacks early and in late afternoon.
what affects the san francisco piranha
cold and cold fronts
Cold water makes the school sluggish.
atmospheric pressure
Little effect.
moon
Little effect.
rain
Little effect.
water level
Low water concentrates schools in pools and lagoons.
noise
Not very sensitive; noise in the water may even attract them.
wind
Little effect.
depth
Mid-water, 0.5 to 4 m.
how to fish
lures
- colher
- jig
- mid-water plug
natural baits
- piece of fish
- carne
- beef heart
tip from an angler
Long-shank hook and wire leader. Never put your hand near the mouth.
- rod
- 6' to 6'6", medium action, 12 to 20 lb
- spinning / baitcasting reel
- spinning reel 2500 to 3000
- line
- braided line 20 lb or monofilament 0.35 mm
- leader
- fine steel leader or fluorocarbon 50 lb
- hook
- #1/0 to 3/0, long shank
accessories
- long-nose pliers
- boga-grip
catch and release
Use long-nose pliers and a lip grip. Release quickly, keeping your hand away from the mouth.
rules for the san francisco piranha
Rules change; before keeping or transporting fish, check with the state environmental agency.
GO (Paranaíba): allochthonous, free capture
no size or bag limitGO details
In the Paranaíba basin in Goiás, piranha caju (Pygocentrus piraya) is in Annex II of the state rule, which lists allochthonous species with free capture and transport.
Source: IN Semad-GO nº 17/2026, art. 5º and Annex II (exotic, allochthonous and hybrid species)
piracema and closed seasons
Each bar is the period when fishing is prohibited or restricted. The green line is today. Tap the name to see what is still allowed.
Spawning closure (piracema) in Minas Gerais (state rule)
Allowed: Only exotic or hybrid species, 3 kg + 1 fish per day, with handline, rod, simple pole, or spinning or baitcasting reel. Nets prohibited. Keep the minimum distances from dams and reservoirs.
Source: Portarias IEF nº 154/2011 (São Francisco), 155/2011 (East) and 156/2011 (Grande/Paranaíba)
Closed season in Goiás (state rule)
Allowed: Sport and guided fishing only in reservoirs, catch and release with barbless hooks (no keeping, transporting or eating). Subsistence: up to 5 kg per day, for household consumption only.
Spawning closure (piracema) in the São Francisco River basin (rivers and reservoirs)
Allowed: Recreational fishing from a boat or from shore with handline, rod, spinning or baitcasting reel, up to 5 kg + 1 fish. Prohibited within 1,000 m of dams, waterfalls and rapids, and within 500 m of confluences. Floodplain lakes have a longer closed season (see next item).
Source: Portaria IBAMA nº 50/2007
São Francisco: floodplain lakes
Allowed: No fishing in the floodplain lakes during the period.
Source: Portaria IBAMA nº 50/2007
Conservation: Not on the national list (Portaria GM/MMA 1.667/2026).
how much it weighs without taking it out of the water
estimated weight
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how we calculate
Length-weight relationship W = a·Lb (a = 0.02239, b = 3.14; FishBase). It's an average: a fat or lean fish can vary by 10% to 20%.
more about the san francisco piranha
Considered the largest piranha, Pygocentrus piraya is native to the São Francisco basin and common in oxbow lagoons and reservoirs. In the Barragem da Pedra reservoir, on the Contas River (BA), its diet was dominated by fins, fish and shrimp. It attacks meat, fish and artificial lures in groups and cuts line easily. Outside its home basin it was moved to Northeast reservoirs, with records in the Jaguaribe River (CE) since the 1960s, and Goiás rules list it as allochthonous in the Paranaíba. In sport fishing it can exceed 3 kg.
Family: Serrasalmidae · predator
fun facts
- It is considered the largest piranha species.
- Fins of other fish often show up in its stomach: it nips more than it kills.
in the kitchen
White, tasty flesh with bones; broth and fried fish are traditional.
similar species
sources and references (8)
The season weights (months), the time of day and the 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 the field experience of anglers and guides. They are not official data nor a measurement made for this species, and they may vary by region and year. Closed seasons and legal rules appear in the rules section, with the norm and a link.
- scientific FishBase — Pygocentrus piraya (ficha da espécie)Names, distribution, biology, length-weight relationship and references. Page checked on October 13, 2026.
- official Portaria GM/MMA nº 1.667, de 27 de abril de 2026 — Lista Nacional Oficial de Espécies da Fauna Ameaçadas de Extinção (peixes e invertebrados aquáticos)Most recent national list. The species is not on it (search by scientific name in the text published in the DOU, checked on October 13, 2026).
- official ICMBio/SALVE — Ficha de Pygocentrus piraya (avaliação nacional do risco de extinção)ICMBio national assessment, published in 2026. DOI checked on Crossref.
- scientific IUCN Red List — Pygocentrus piraya (avaliação global: Pouco Preocupante, LC, 07/11/2018)Global assessment. Link given on the FishBase entry (Red List, version 2025-2).
- scientific Trindade, M. E. J.; Jucá-Chagas, R. (2008). Diet of two serrasalmin species, Pygocentrus piraya and Serrasalmus brandtii (Teleostei: Characidae), along a stretch of the rio de Contas, Bahia, Brazil. Neotropical Ichthyology 6(4): 645–650.Diet in the Barragem da Pedra reservoir. DOI and abstract checked in Crossref.
- scientific Paiva, M. P. (1965). On a pelvicless specimen of Pygocentrus piraya (Cuvier, 1820) from Jaguaribe River basin, Brazil. Copeia 1965.Old record of the species in the Jaguaribe basin (CE). DOI checked in Crossref.
- official IN Semad-GO nº 17/2026 — normas de pesca em Goiás (Anexos I e II)Annex II lists exotic, allochthonous and hybrid species with free capture and transport. Text checked on Oct 13, 2026.
- scientific Pessali, T. C. et al. (2022). Length-weight relationships of 78 fish species from São Francisco River basin, Brazil. Journal of Applied Ichthyology.Length-weight relationship and maximum size used in FishBase for the species.
how we calculatewhere 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: