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catalog Hypopomidae · omnivore

itui

Brachyhypopomus pinnicaudatus

Freshwateressential profile

A small knifefish, up to 18.6 cm, that lives in still, oxygen-poor waters of eastern South America. It has commercial and aquarium use but is not a target of sport fishing.

Also called: itui, tuvira

forecast for itui where found
Scientific illustration of Itui
maximum
19 cm
overview

who is the itui

The itui belongs to the family Hypopomidae, the knifefishes: body elongated and flattened from side to side, with a very long anal fin and no dorsal fin. Reaches 18.6 centimeters. It lives in still waters of low conductivity and low oxygen, among floating and emergent plants along the shallow edges of streams. It occurs from the Catatumbo, the Orinoco and the Guianas to the La Plata basin, and in the Peruvian Amazon. When oxygen is scarce, it can breathe air from the surface. It has commercial and aquarium use and is hardly ever caught on a rod.

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 itui; in the meantime, see the similar species.

fun facts

  • It can breathe atmospheric air when the water becomes low in oxygen.
how to recognize it

identification

An elongated knifefish with a body flattened from side to side, no dorsal fin and a very long anal fin running along most of the belly. Reaches 18.6 centimeters, less than the floating tuvira (Brachyhypopomus beebei), at 32, and the large itui (Hypopomus artedi), at 50. It lives in still waters, while the large itui lives in fast-flowing streams.

how itui fishing looks

Loading the next 7 days…

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.

distribution

where found

open on the large map

It occurs in eastern South America, from the Catatumbo, the Orinoco and the Guianas to the La Plata basin, and in the Peruvian Amazon, in Brazil, Bolivia, Colombia, Ecuador, Paraguay, Peru, Uruguay and Venezuela.

Habitat: Still, oxygen-poor waters, along the shallow edges of streams, with floating and emergent plants.

native to the basins

AmazonTocantins-AraguaiaParanáParaguay (Pantanal)
what the law says

rules for the itui

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 the Paraná River basin

01/11 to 28/02SPPRMGGOMSDF

Allowed: Recreational fishing only for non-native species and hybrids (peacock bass, tilapia, black bass, carp, croaker, etc.; piauçu remains prohibited), with handline, simple pole, or rod with spinning or baitcasting reel, up to 10 kg + 1 fish. In rivers, from shore only; in reservoirs, from a boat or from shore. Prohibited: floodplain lakes, aquatic-animal bait, within 1,500 m of dams and waterfalls, and within 500 m of confluences. Tournaments only in reservoirs and only with non-native species.

Source: IN IBAMA nº 25/2009

Closed season in Goiás (state rule)

01/11 to 28/02GO

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.

Source: IN Semad-GO nº 17/2026, arts. 8º to 11

Spawning closure (piracema) in the Pantanal of Mato Grosso do Sul

05/11 to 28/02MS

Allowed: Subsistence fishing by riverside residents and authorized scientific fishing. Decree 15.166/2019 (art. 11, §5) allows catch and release only in February and only in the channels of the Paraguay and Paraná rivers. For the rest of the period, not even catch and release is allowed. Check the Imasul portaria for each season.

Source: Decreto estadual MS nº 15.166/2019, art. 11; IN IBAMA nº 201/2008

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.

Source: IN Interministerial MAPA/MMA nº 10/2017; Resolução Cepesca-MT nº 1/2026; Lei estadual MT nº 9.096/2009, arts. 19-A and 27 (Leis 12.434/2024 and 13.159/2025)

Spawning closure (piracema) in the Araguaia River basin

01/11 to 28/02GOTOPAMT

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.

Source: IN Interministerial MPA/MMA nº 12/2011

Spawning closure (piracema) in the Tocantins and Gurupi river basins

01/11 to 28/02TOPAMAGO

Allowed: Recreational fishing only in reservoirs, with on-site consumption. Subsistence: 5 kg + 1 fish. State rules may be stricter.

Source: IN Interministerial MPA/MMA nº 13/2011

Closed season in the rivers of Marajó Island (PA)

01/01 to 30/04PA

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

Closed season in the Amazon basin in Amapá

15/11 to 15/03AP

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

Border rivers MT/RO and MT/PA

05/11 to 28/02MTROPA

Allowed: See the exceptions in Portaria 48/2007 and the state rules for each bank.

Source: Portaria IBAMA nº 48/2007

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.

It is not dangerous. Since its body is smooth and slippery, hold it with wet hands and return it to the water promptly.

calculator

how much it weighs without taking it out of the water

Length-weight relationship W = a·Lb (a = 0.00372, 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

—

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.

  1. scientific FishBase: Brachyhypopomus pinnicaudatus (ficha da espécie)Size, length-weight, depth, habitat, distribution, biology, and IUCN status. Page checked on Oct 13, 2026.
  2. scientific FishBase: nomes populares de Brachyhypopomus pinnicaudatusNames by country and language.
  3. 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.
don't confuse

similar species

Illustration of Tuvira-flutuante
Hypopomidae

Tuvira-flutuante

Brachyhypopomus beebei

Knifefish that reaches 32 cm and lives in tropical fresh waters, near floating plants. It has commercial and aquarium use, but is not a target of sport fishing.

Freshwater
Illustration of Itui-grande
Hypopomidae

Itui-grande

Hypopomus artedi

A knifefish that reaches 50 cm, the largest of the itui and tuvira group. It lives in fast-flowing streams of the Guianas and Brazil, and has commercial and aquarium use.

Freshwater