skipjack tuna
Katsuwonus pelamis · Scombridae · predator
A small, fast, hard-fighting open-sea tuna. Fun on light tackle and the favorite bait for marlin.
Also called: bonito, bonito-de-barriga-listrada, skipjack
- common size
- 40–75 cm
- maximum
- 110 cm
- common weight
- 1.5–8 kg
- record/max.
- 34.5 kg
- depth
- 0–100 m
- ideal water
- 21–28 °C
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.
Reading the weather across 3 global models and 31 simulations…
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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
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.
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 skipjack tuna
who is the skipjack tuna
The skipjack tuna is the most fished tuna in the world and the main target of the pole-and-live-bait fleet in the Southeast and South. It travels in large, fast schools at the surface, hunting sardines, anchovies, and squid, and gives away its presence with diving birds and boiling water. It rarely exceeds 10 kg on the Brazilian coast, but on light tackle it makes strong runs. For the offshore angler it has two roles: fun between strikes, and bait, live or dead, for marlin, tunas, and wahoo. The flesh is dark and strong, good fresh and excellent canned.
fun facts
- It is the main tuna in the canned tuna sold in Brazil.
- The pole-and-live-bait fleet throws live sardines and jets of water to keep the school in a frenzy alongside the boat.
identification
Rounded, short, thick body. Purplish-blue back, with no pattern. Its mark is 4 to 6 dark horizontal stripes on the lower flank and belly. The spotted bonito has wavy patterns on the back and black spots below the pectoral, with a plain belly. Juvenile yellowfin tuna has pale spots in vertical rows on the belly and yellowish fins.
where found
Outer shelf and open sea, from the Northeast to Rio Grande do Sul. In the Southeast and South it is abundant in summer between Cabo Frio-RJ and Santa Catarina, off Rio de Janeiro, Santos-SP, and Itajaí-SC. Also common at Vitória-ES, where it is the most used bait for blue marlin, and off Natal-RN.
Habitat: Surface and the 0 to 100 m layer, at current edges and thermal fronts, almost always behind schools of bait.
coast
states
Rio Grande do Norte, Paraíba, Pernambuco, Alagoas, Sergipe, Bahia, Espírito Santo, Rio de Janeiro, São Paulo, Paraná, Santa Catarina, Rio Grande do Sul
when to fish
best season
In the Southeast and South the season runs from December to April, with warm water and sardines. In the Northeast it appears all year.
best time of day
Daytime, with peaks at dawn and dusk. Hunts at the surface from dawn to mid-morning and again in late afternoon. In strong sun it sinks and surfaces in quick feeding frenzies.
what affects the skipjack tuna
sensitivity The little bars show how much each factor affects this species. Five full: it feels it a lot.
cold and cold fronts
Below 19 °C the schools disappear from the surface.
atmospheric pressure
A cold front scatters the schools; they return when the sea settles and the blue water comes back.
moon
Small effect.
rain
Light rain doesn't bother. Thunderstorm with lightning: head back.
water level
Not applicable at sea. The equivalent is the color and clarity of the water: look for blue, clean water and current lines.
noise
The school sinks if the boat passes over it. Approach from the front and shut off or slow the motor.
wind
Light swell helps hide the line; strong wind makes it hard to see birds and feeding frenzies.
tide
Little effect in open sea.
depth
Surface down to 100 m. Follow the birds: they show where the school is pushing the bait.
how to fish
- rod
- 6'6" to 7'6", 12 to 25 lb
- spinning / baitcasting reel
- 4000 to 6000 spinning reel or light 12 to 20 lb trolling baitcaster
- line
- braid 20 to 30 lb
- leader
- fluorocarbon 30 to 50 lb, 1 to 1.5 m
- hook
- 2/0 to 4/0 single or reinforced treble hook; assist hook on jigs
lures
- 30 to 60 g casting jigs
- 9 to 12 cm stickbaits
- small squid and trolling feathers
- streamers on fly (line 8 to 10)
natural baits
- live sardine
- manjuba
accessories
- luvas
- insulated cooler with ice
tip from an angler
Don't run the boat over the school. Get ahead of its swimming direction, slow the motor, and cast the jig to the edge of the feeding frenzy, retrieving fast.
ocean trolling (blue marlin, mahi-mahi and tuna)
Boat fishing at the shelf edge and in open sea, trolling artificial or natural baits at speed, after marlin, mahi-mahi and tuna.
guidefish preservation and cleaning
Quick killing, bleeding, the right amount of ice, a well-used cooler, filleting and transport within the law. Fish handled well on the boat is worth twice as much at the table.
rules for the skipjack tuna
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: Western Atlantic stock managed by ICCAT.
We found no species-specific rule beyond the region's general rules.
catch and release
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.
Small tuna die quickly out of the water. Release them without touching the gills, head down in the water, with a push.
in the kitchen
Dark, strong-flavored flesh. Bleed it right away. Good grilled, pickled (escabeche), smoked, or canned; raw only when very fresh.
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.01072, b = 3.11; FishBase (estimativa bayesiana, 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 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 — Katsuwonus pelamis (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 Katsuwonus pelamis (avaliação nacional do risco de extinção)ICMBio national assessment, published in 2025. DOI checked on Crossref.
- scientific IUCN Red List — Katsuwonus pelamis (avaliação global: Pouco Preocupante, LC, 15/01/2021)Global assessment. Link given on the FishBase entry (Red List, version 2025-2).
- scientific Collette, B. B.; Nauen, C. E. (1983). FAO species catalogue. Vol. 2. Scombrids of the world. FAO Fisheries Synopsis 125(2). Roma: FAO.
- technical ICCAT Manual, cap. 2.1.3 — Skipjack tuna (Katsuwonus pelamis). International Commission for the Conservation of Atlantic Tunas.Biology and fishery of the species in the Atlantic.
- scientific Carpenter, K. E. (org.) (2002). The living marine resources of the Western Central Atlantic. Vol. 3: Bony fishes part 2 (Opistognathidae to Molidae). FAO Species Identification Guide for Fishery Purposes. Roma: FAO.Scombridae chapter (Collette, B. B.).
similar species
where 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: