slender tuna
Allothunnus fallai
Slender tuna of the Southern Ocean, which appears in waters of Brazil, Uruguay, Argentina, Chile and Peru. It has a small commercial fishery and its flesh is sold mainly fresh.
Also called: atum-esguio, atún lanzón, slender tuna
- maximum
- 105 cm
- record/max.
- 13.7 kg
- depth
- 0–20 m
who is the slender tuna
The slender tuna is a fish of the family Scombridae, with a fusiform, slender body, reaching 105 cm and up to 13.7 kg. It lives in open sea, in waters from 0 to 20 m, in a band that circles the Southern Ocean, and sometimes forms schools. It feeds mainly on krill and also on squid and small fish. Juveniles appear between 20° and 35° south latitude. It has a small commercial fishery and is considered a sport fish.
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 slender tuna; in the meantime, see the similar species.
fun facts
- One specimen was found in the port of Los Angeles, USA.
identification
Fusiform body, with bluish back that turns dark purple, almost black, on the head. The belly is white, with no stripes or spots. The pectoral and pelvic fins are purple, with the inner part black. Unlike the southern bluefin tuna, which has lines and dots on the belly, the belly of this species is smooth.
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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.
Essential profile: the index uses a general fish model (weather, sun, moon and tide), without a season or time of day specific to this species.
where found
Lives in the Southern Ocean, in a circumglobal band, and appears in waters of Brazil, Uruguay, Argentina, Chile and Peru.
Habitat: Open sea, mainly at the surface and in waters 0 to 20 m.
coast
rules for the slender 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: Not on the Brazilian national list (Ministerial Ordinance GM/MMA No. 1.667/2026).
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.
Harmless to handle. Like all tuna, keep it on ice right after capture.
in the kitchen
The flesh is lighter than that of common tunas and very oily, but cooked it is of good quality, and it is sold mainly fresh.
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.00933, b = 3.06; FishBase (relação peso-comprimento bayesiana, estimativa)). It's an average: a fat or lean fish can vary by 10% to 20%.
estimated weight
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sources and references
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.
- scientific FishBase: Allothunnus fallai (ficha da espécie)Size, length-weight, depth, habitat, distribution, biology, and IUCN status. Page checked on Oct 13, 2026.
- scientific FishBase: nomes populares de Allothunnus fallaiNames by country and language.
- 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)The species is not on the list. Checked in the DOU of April 28, 2026.
