otuno
Olivaichthys viedmensis
Freshwater catfish from Argentina, from the Negro River basin and tributaries, reaching 32.4 cm. It lives on the bottom of subtropical rivers.
Also called: bagre-aveludado, bagre-aterciopelado, otuno, gatuno
- maximum
- 32 cm
who is the otuno
The otuno is a freshwater catfish of the family Diplomystidae, reaching 32.4 cm, large for the family. It lives on the bottom of rivers, in a subtropical environment, in the Negro River basin and its tributaries, in Argentina. Like other Diplomystidae, it has no scales and a flattened head. In Argentina it is known locally as gatuno and otuno. No commercial or sport use has been recorded for the species, and it is hardly ever caught on rod and line.
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 otuno.
fun facts
- In Argentina it is known by the common names gatuno, otuno and bagre aterciopelado.
identification
Elongated, bottom-dwelling catfish of the family Diplomystidae, without scales and with a flattened head. It reaches 32.4 cm, large for the family. Its range is the Negro River basin, in Argentina, where it is known locally as gatuno and otuno.
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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
Negro River basin and its tributaries, in Argentina, in subtropical fresh water.
Habitat: Bottom of subtropical fresh waters in the Negro River basin, in Argentina.
rules for the otuno
Summary of the regulations we found, with the source for each. Rules change; before keeping or transporting fish, check with the state environmental agency.
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.
No known danger to anglers. Release it with a wet hand and do not keep the fish out of the water for long.
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.00457, b = 3.12; 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: Olivaichthys viedmensis (ficha da espécie)Size, length-weight, depth, habitat, distribution, biology, and IUCN status. Page checked on Oct 13, 2026.
- scientific FishBase: nomes populares de Olivaichthys viedmensisNames by country and language.