The bagre-arenoso is of the family Ariidae and reaches 25 cm. It lives in coastal rivers that flow into the Atlantic, from Guyana to northeastern Brazil, in fresh water, near the bottom and in midwater. It is a scaleless catfish with smooth skin. Like the other catfish of the family, it has strong spines on the dorsal and pectoral fins that hurt whoever handles it. It is caught for commercial sale and rarely shows up on the line of rod anglers.
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 bagre-arenoso; in the meantime, see the similar species.
how to recognize it
identification
Scaleless catfish with a flattened head and barbels around the mouth, like the other ariids. It has strong spines on the dorsal and pectoral fins that call for care when handling. It reaches 25 cm. It looks very much like Cathorops agassizii and the bagre-amarelo (Cathorops spixii), from the same genus; telling the three apart in the field is hard, so treat them all with the same caution around the spines.
how bagre-arenoso fishing looks
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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.
Atlantic coastal rivers, from Guyana to northeastern Brazil, passing through Suriname and French Guiana.
Habitat: Coastal freshwater rivers, from the bottom to midwater.
native to the basins
AmazonWestern Northeast Atlantic
what the law says
rules for the bagre-arenoso
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.
piracema closures in the basins where the species lives
Spawning closure (piracema) in Mato Grosso (all basins)
01/10 to 31/01MT
Allowed: All fishing modalities are prohibited in rivers, including catch and release (Law 9.096/2009, art. 19-A). Exceptions: subsistence fishing from shore (3 kg or 1 fish, no transport or sale) and scientific fishing. Law 13.159/2025 now allows licensed sport fishing in UHE/PCH hydropower reservoirs, natural lakes and border rivers, subject to a scientific study and a license from the environmental agency. We have not confirmed whether these licenses are already being issued.
Allowed: Recreational fishing from a boat or from shore with handline or rod, up to 5 kg or 1 fish. Transport only within the municipality. Competitions prohibited.
Allowed: Recreational anglers with handline or rod, line and hook are outside the Annex II prohibitions, with a bag limit of 5 kg + 1 fish, unless a stricter state rule applies.
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.
The spines on the dorsal and pectoral fins cut: hold it with a cloth, take the hook out with pliers and release it.
calculator
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.00468, b = 3.13; 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.
