Brycon amazonicus · Bryconidae · omnivore
Silvery, nervous fish of fast rivers, jumps a lot and eats everything: fruit, insects and small fish.
Also called: matrinxã, matrinchã, jatuarana
Choose the place and the species. The index, from 0 to 100, combines weather, sun, moon and tide with each fish's habits. Up to 28 days, with each day's confidence.
Reading the weather across 3 global models and 31 simulations…
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.
Choose how many fishing days. We compare each stretch by its average index, discount days with a warning or closed season, and show the 3 best.
Line: the middle value of 31 simulations of the American GEFS model. Band: where 8 out of 10 fall. Narrow, firm trend; wide, high uncertainty.
Matrinxã is a streamlined, fast and very jumpy fish, typical of fast rivers and banks with fruit trees. It eats fruit, seeds, flowers, insects that fall into the water and small fish. It migrates to spawn at the start of high water, when it swims upriver in large schools. In the dry season it stays in rapids, rocky bottoms and shaded banks. In sport fishing it is highly prized on light tackle and fly, since it strikes spoons, small lures and flies and fights with jumps and runs. It is also farmed and widely eaten in Amazonas.
Elongated, silvery body, grey-olive back, diffuse dark blotch behind the head and dark caudal fin. Lower fins orange. Small scales and a mouth with teeth in several rows. The Pantanal piraputanga has a reddish tail with a black band and does not occur in the Amazon. On the Araguaia and the Teles Pires, the local matrinchã is usually another, very similar Brycon species.
Amazon channel and tributaries, including the Negro, Branco and Madeira. In Mato Grosso the name matrinchã also covers other Brycon species from the Teles Pires, Juruena and Araguaia.
Habitat: Rapids, rocky bottoms, banks with fruit trees, clearwater igarapés and flooded forest in high water.
native to the basins
states
Amazonas, Pará, Roraima, Acre, Rondônia, Amapá, Mato Grosso
Falling water and dry season, June to October, concentrate fish in rapids and along banks. At the start of high water it swims up the rivers to spawn.
Daytime, with peaks at dawn and dusk. Active by day, peaking early in the morning and late in the afternoon, when it hunts insects on the surface.
Friagem reduces surface activity.
Stable weather helps.
Little effect.
Heavy rain muddies the water and hampers spoon fishing.
A falling river exposes rocky bottoms and rapids where it concentrates.
Very wary in clear water. Approach slowly and cast far.
Wind knocks down fruit and insects and can get the fish going.
Surface and mid-water in current and along the bank.
lures
natural baits
accessories
Cast the spoon upstream and reel slightly faster than the current. Keep the line tight during jumps.
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). Other Brycon species are threatened, such as the Tocantins piabanha (B. gouldingi, VU).
Matrinxã is on the list of banned species from November 15 to March 15 in Amazonas, Acre and Amapá. In Rondônia (Madeira basin) and in Pará the ban appears under the name jatuarana.
Until December 31, 2028, matrinchã (the whole genus Brycon) caught in Mato Grosso rivers may not be transported, stored or sold. Amateur 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
Annual closed season in AM for the species in Annex II of Portaria 48/2007: pirapitinga, mapará, sardine, pacu, aruanã and matrinxã. Tambaqui and arapaima (pirarucu) have their own rules (see the specific items and "prohibitions").
Source: Portaria IBAMA nº 48/2007
Annual closed season in AC for the species in Annex II: dourada, piraíba, pirapitinga, caparari, aruanã, jaraqui, mapará, sardine, matrinxã and pacu. On the Acre River, the closed season applies to all species (IN IBAMA 205/2008).
Source: Portaria IBAMA nº 48/2007; IN IBAMA nº 205/2008 (Acre River)
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.
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: 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
Sensitive fish: remove the hook in the water, without squeezing the belly, and release it quickly. Avoid letting it thrash on the bottom of the boat.
Very tasty flesh, but with Y-shaped bones. Grilled over coals, fried in thin cuts or in fish stew.
Length-weight relationship W = a·Lb (a = 0.01445, b = 3.06; FishBase (bayesiano, espécie + gênero)). 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.
The weather comes from three independent global models, cross-checked hour by hour: when they agree, confidence goes up; when they diverge, the band between them shows on the chart. Beyond 16 days, we use the GEFS ensemble of 31 simulations: if 20 of the 31 predict rain, the chance of rain is 65%. Sun and moon are calculated astronomically, with no uncertainty.
The index adds up, weighted for each species: time of day (species curve anchored to real sunrise and sunset), moon (transits, rise and set, phase), pressure (3 h trend and 24 h swing), water temperature (in rivers, estimated from air temperature; at sea, estimated by an ocean model), wind, rain, clouds, tide and the month in the species' cycle.
Accuracy measured in the reference project (4 regions, 93 days, forecast vs. observed): maximum temperature is off by 0.6 °C on average the next day and 1.7 °C at 7 days; rain of 5 mm or more is detected 76% of the time the next day and 57% at 7 days. Detection isn't everything: the false alarm rate isn't published here yet, and 93 days in 4 regions is still a small sample. We now also measure every day, at the app's destinations:
Your location is saved only on this device and feeds the forecast, the map and the "today" on the home page.
