Hoplias aimara
The trairão, the giant trahira of the clear-water rivers of the Brazilian Shield. Brutal surface strikes and teeth that cut through anything.
Also called: trairão, aimara
The trairão is the largest species in the trahira genus and lives in clear-water rivers flowing from the Central Plateau and the Guianas, such as Teles Pires, Juruena, Xingu, Tapajós and Trombetas. It lies in ambush in backwaters, pools, submerged timber and shaded shorelines and makes explosive strikes at fish, frogs and even small mammals. It has strong canine teeth, a powerful jaw and thick skin. In sport fishing it is sought for its violent strike on surface lures and for the strong fight in the first seconds. It often misses strikes, so keep working the same spot. It tolerates low oxygen and stays a long time in the same pool.
Cylindrical, thick body, large head and a mouth full of canine teeth. Dark brown to almost black back, lighter flanks with blotches and a large dark spot on the gill cover. Rounded tail with no adipose fin. The common trahira is much smaller and lacks the strong gill-cover spot. Adult trairão easily exceeds 5 kg.
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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.
Clear-water rivers of the Brazilian Shield and the Guianas: Teles Pires, Juruena, São Benedito, Xingu, Iriri, Tapajós, Trombetas, Jari and tributaries of the Tocantins.
Habitat: Backwaters, rapids pools, submerged timber, shaded shorelines and side lagoons of clear-water rivers.
native to the basins
states
Mato Grosso, Pará, Amapá, Amazonas, Tocantins, Roraima
The dry season, from June to October, is the peak season in the rivers of Mato Grosso and Pará: low water, clear water and fish in the pools.
Dawn and dusk. Most active early in the morning, late in the afternoon and at night. During the day it strikes in the shade of submerged timber and banks.
A cold snap (friagem) reduces strikes for a day or two.
Moderate effect.
Clear moonlit nights favor night surface fishing.
Little effect, except when it muddies the water.
Low water concentrates trairão in pools and backwaters.
Moderately sensitive. Approach small pools without a running motor.
Little effect on rivers with riparian forest.
Shallow and in the shade; rarely below 4 m.
lures
natural baits
accessories
The trairão misses a lot of strikes. If it attacked and didn't take the lure, cast again to the same spot and work the lure more slowly.
Casting in lagoons, marshes, small reservoirs and vegetated reservoir edges, using frogs, sapito, zara and buzzbait.
ready-made kitTrip on a live-aboard boat or at a lodge on the Rio Negro and its tributaries, in the dry season, after speckled peacock bass with surface and mid-water lures.
guideWhere fish are in each type of water, from rapids and swirls to bay mouths and corixo channels, and how river level changes everything.
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).
Until Dec 31, 2028, trairão caught in rivers of Mato Grosso may not be transported, stored or sold. Recreational anglers may only practice catch and release.
Source: Lei estadual nº 12.434/2024 (MT), arts. 19-B and 19-C of Lei 9.096/2009
In Tocantins the trairão may only be kept if it is 50 cm or longer. The regulation lists trairão as Hoplias curupira, a species from near the Tocantins basin.
Source: Portaria NATURATINS/GABIN nº 47/2026 (annexes amended by Portaria nº 105/2026)
Transport, storage and sale are fully prohibited for 5 years from Jan 1, 2024 for: cachara, caparari, dorado, jaú, matrinchã (Brycon spp.), pintado/surubim (Pseudoplatystoma spp.), piraíba, piraputanga, pirarara, arapaima (pirarucu), trairão and peacock bass (tucunaré, Cichla spp.). For recreational anglers: catch and release only. These 12 species may not even be eaten on site, since the 2 kg or 1 fish limit excludes the art. 19-B list. The law cites jaú as Zungaro zungaro; we also include the Pantanal jaú (Z. jahu) out of caution. The list may still change: § 2 (exotic and predatory species), § 3 (review through study) and the 3-year assessment planned for 2027. A TJMT news report of Jun 2, 2026 confirms the 12 prohibited species. The STF denied a preliminary injunction in the ADIs against the law in 2024; we found no merits ruling.
Source: Portaria Naturatins nº 47/2026, Annex I, as amended by Portaria nº 105/2026
Allowed: Sport and guided fishing only in reservoirs, catch and release with barbless hooks (no keeping, transporting or eating). Subsistence: up to 5 kg per day, for household consumption only.
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 only in reservoirs, with handline, rod, or spinning or baitcasting reel. Fish may only be eaten on site, not transported. Competitions prohibited. Subsistence: 3 kg + 1 fish. State rules (GO and TO) may be stricter.
Allowed: Recreational fishing only in reservoirs, with on-site consumption. Subsistence: 5 kg + 1 fish. State rules may be stricter.
Allowed: In 2025/26: catch and release with barbless hooks and recreational fishing card; subsistence fishing on foot or from a rowboat, with simple pole or handline.
Source: Portaria Naturatins nº 244/2025 (2025/26 season); INIs MPA/MMA nº 12 and 13/2011
Allowed: The same recreational-angler exceptions as in Portaria 48/2007 apply (handline or rod, 5 kg + 1 fish), unless a stricter state rule applies.
Source: Portaria IBAMA nº 48/2007
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.
Source: Portaria IBAMA nº 48/2007
Allowed: Subsistence fishing only.
Source: Portaria IBAMA nº 48/2007
Allowed: See the exceptions in Portaria 48/2007 and the state rules for each bank.
Source: Portaria IBAMA nº 48/2007
Never put your hand in its mouth. Use a heavy-duty boga-grip and long pliers, support the heavy body and release it in the shade. A tired big fish takes a long time to recover.
White, firm flesh but with Y-shaped bones like the trahira. Good fried in thin steaks or baked.
Length-weight relationship W = a·Lb (a = 0.00741, b = 3.13; FishBase (bayesiano, espécie + forma do corpo da família)). It's an average: a fat or lean fish can vary by 10% to 20%.
estimated weight
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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.
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