black jack
Caranx lugubris · Carangidae · predator
Dark jack of clear oceanic waters, from islands, distant submerged reefs, and shelf edges. Fights hard on jigging and popping.
Also called: xaréu-preto, xeréu-preto, ferreiro, black jack
- common size
- 50–80 cm
- maximum
- 100 cm
- common weight
- 2–8 kg
- record/max.
- 17.9 kg
- depth
- 12–150 m
- ideal water
- 24–28 °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
tap or drag on the chart to read each hour · on a keyboard, arrow keyssee 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 black jack
who is the black jack
The black jack is a carangid of clear oceanic waters, typical of islands, banks, and shelf edges, and uncommon on shallow banks near the coast. In Brazil it appears mainly around the oceanic islands, such as Fernando de Noronha, São Pedro e São Paulo, and Trindade, and on banks and submerged reefs far from the coast; the islands have conservation units with their own fishing rules. It lives from 12 to over 300 m, almost always between 25 and 65 m, sometimes in schools by the reef drop-offs. It hunts fish, mostly at night. For the sport angler it is a strong opponent on vertical jigging and popping. The flesh is eaten, but ciguatera cases linked to the species have been recorded in other regions.
fun facts
- It is one of the few carangids with a circumtropical distribution.
- It is restricted to clear oceanic waters and rarely enters shallow coastal banks.
identification
Deep, robust body, dark gray to almost black, sometimes olive-brown, with a sloping head profile. Dark lateral line scutes. Long, sickle-shaped lobes on the second dorsal and anal fins. Differs from the crevalle jack (C. hippos) by its uniform dark color, the lack of a black spot on the operculum and at the pectoral base, and its steeper head profile.
where found
Oceanic islands (Fernando de Noronha, São Pedro e São Paulo, Trindade) and banks, submerged reefs, and shelf edges from the Northeast to the Southeast.
Habitat: Clear oceanic waters, reef edges, shelf edges, oceanic islands, and submerged reefs far from shore; usually 25 to 65 m.
coast
states
Rio Grande do Norte, Pernambuco, Bahia, Espírito Santo, Rio de Janeiro
when to fish
best season
Present all year around the islands and banks; sea conditions decide the fishing.
best time of day
Dawn and dusk. Hunts most at dawn, at dusk, and at night; by day it responds well to jigs at the drop-offs.
what affects the black jack
sensitivity The little bars show how much each factor affects this species. Five full: it feels it a lot.
cold and cold fronts
Cold bottom water keeps the fish deeper and slower.
atmospheric pressure
Moderate effect.
moon
Big moons concentrate night hunting.
rain
Not very sensitive.
water level
Prefers blue, clear water.
noise
Not very sensitive at depth.
wind
Rough seas prevent fishing on distant banks.
tide
Current at the reef drop-offs concentrates baitfish and jacks.
depth
25 to 65 m for most catches.
how to fish
- rod
- jigging PE 3 to 5; popping 7'6" to 8'0" PE 4 to 6
- spinning / baitcasting reel
- 8000 to 14000 spinning reel or jigging baitcaster
- line
- braided PE 3 to 6 (40 to 80 lb)
- leader
- fluorocarbon or monofilament 60 to 100 lb, 2 m
- hook
- assist hooks 5/0 to 7/0; reinforced single hooks on the poppers
lures
- 100 to 250 g jigs
- 14 to 20 cm poppers and stickbaits
natural baits
- live baitfish (xixarro, sardine)
- lula
accessories
- luvas
- fighting belt
- alicate
tip from an angler
After the hookset, pull hard in the first few meters to get the fish away from the rock.
rules for the black jack
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: Not on the national list (Portaria GM/MMA 1.667/2026). At the oceanic islands, the rules of the conservation units apply.
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.
If it comes from depth, it suffers barotrauma: use a descending device and release it quickly.
in the kitchen
Dark, firm flesh; beware of ciguatera risk in large reef fish.
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.01738, b = 2.96; 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 — Caranx lugubris (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 Caranx lugubris (avaliação nacional do risco de extinção)National assessment by ICMBio, published in 2023. DOI verified on Crossref.
- scientific IUCN Red List — Caranx lugubris (avaliação global: Pouco Preocupante, LC, 20/08/2012)Global assessment. Link given on the FishBase entry (Red List, version 2025-2).
- 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.Carangidae chapter (Smith-Vaniz, W. F.), cited by FishBase for the species.
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: