The three-spot piau belongs to the family Anostomidae and reaches 19 cm. It occurs in the Amazon basin, with records in the Guaporé River in Brazil, and in rivers of the Guianas, Ecuador, Peru and Argentina. Adults form schools of 10 to 50 individuals in deeper water. It eats plants, and pairs breed in places with dense vegetation. It has commercial use and is also sold for aquariums, but it hardly ever turns 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 threespot headstander; in the meantime, see the similar species.
how to recognize it
identification
Spindle-shaped body, with dark transverse bars on the back and usually two dark spots in the middle of the flank, sometimes three or four. The scientific name, trimaculatus, refers to the three spots, but the number varies. Do not confuse it with the three-spot leporinus (Leporinus friderici), which is much larger and has three round, distinct dots. This one reaches 19 cm and lives in schools in deeper water.
how threespot headstander 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.
Amazon basin, with a record in the Guaporé River in Brazil, and in rivers of the Guianas (Essequibo and Rupununi), Ecuador, Peru and Argentina.
Habitat: Deeper waters of rivers, in schools of 10 to 50 fish, with dense vegetation for spawning.
native to the basins
Amazon
what the law says
rules for the threespot headstander
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 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.
Small fish: take the hook out carefully, in the water, and release it quickly.
calculator
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.01072, b = 3.04; 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.
