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catalog Lebiasinidae · forage fish

blackmouth pyrrhulina

Pyrrhulina melanostomus

Freshwateressential profile

A small fish of the family Lebiasinidae, with records in Pará, in the Amazon, and also reported from Argentina. It has only potential interest for fishing.

Also called: piaba-de-boca-preta, guaija, blackmouth pyrrhulina

Scientific illustration of Blackmouth pyrrhulina
overview

who is the blackmouth pyrrhulina

The black-mouth piaba belongs to the family Lebiasinidae, the family of small, slender-bodied fishes such as the pencilfishes and the guaijas. The scientific name, melanostomus, means black mouth. It lives in tropical fresh water, from the bottom to midwater. It is recorded from Brazil and Argentina, and in Brazil there are records in Pará, in the Tapajós and lower Tocantins basins. For fishing it has only potential interest and is not a target for sport 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 blackmouth pyrrhulina.

how to recognize it

identification

A small, slender fish of the family Lebiasinidae. The scientific name, melanostomus, means black mouth, and that is the mark for recognizing it, together with the name in other languages, which refers to its dark mouth. Pencilfishes (Nannostomus) are relatives in the same family, but they have dark stripes along the body, while this species is recognized by its dark mouth.

how blackmouth pyrrhulina 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.

distribution

where found

open on the large map

Recorded from Brazil and Argentina. In Brazil there are records in Pará, in the Tapajós and lower Tocantins basins.

Habitat: Tropical fresh water, from the bottom to midwater.

native to the basins

AmazonTocantins-Araguaia
what the law says

rules for the blackmouth pyrrhulina

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

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 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. It is small and delicate: handle it with wet hands, only if necessary, 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 = 0.00661, 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.

  1. scientific FishBase: Pyrrhulina melanostomus (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 Pyrrhulina melanostomusNames 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.