the right time
to be on the water
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.
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hour by hour
slide your finger or mouse over the chart to see each hoursee hour-by-hour table
why this index at —?
choose the day
the fishing month at a glance
what's the best window for the crew?
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.
trend for the coming weeks
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.
everything about the spotstripe pencilfish
how to recognize it
A minuscule, slender, elongated fish of the pencilfish family, with a dark stripe and a spot along the body, as its name in other languages indicates. Reaches 2.4 centimeters, less than the shining pencilfish (3.5 cm) and the elegant pencilfish (3.6 cm), but the three live in different places: this one in the Aripuanã, the shining one in the Capim River and the elegant one near Santarém.
Also called: peixe-lápis, peixe-lápis-de-listra-e-mancha, spotstripe pencilfish
don't confuse with:
We don't have tips on season, bait or technique for this species yet.
where found
open on the large mapWhere to look: Tropical fresh waters, from the bottom to midwater.
Known from two localities in Brazil, in Amazonas: the place where it was described and Castanhal Island, in the Aripuanã River.
native to the basins
rules for the spotstripe pencilfish
Rules change; before keeping or transporting fish, check with the state environmental agency.
We found no species-specific rule beyond the region's general rules.
piracema and closed seasons
Each bar is the period when fishing is prohibited or restricted. The green line is today. Tap the name to see what is still allowed.
Spawning closure (piracema) in Mato Grosso (all basins)
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.
Closed season in the rivers of Marajó Island (PA)
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
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
Closed season in Roraima
Border rivers MT/RO and MT/PA
Allowed: See the exceptions in Portaria 48/2007 and the state rules for each bank.
Source: Portaria IBAMA nº 48/2007
Conservation: Not on the Brazilian national list (Ministerial Ordinance GM/MMA No. 1.667/2026).
how much it weighs without taking it out of the water
estimated weight
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how we calculate
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%.
more about the spotstripe pencilfish
The striped-and-spotted pencilfish belongs to the family Lebiasinidae, the pencilfishes, with a slender, elongated body and small fins. Reaches 2.4 centimeters, a minuscule size even among pencilfishes. It lives in tropical fresh waters, from the bottom to midwater. It is known from only two localities in Brazil: the place where it was described and Castanhal Island, in the Aripuanã River, in Amazonas. Because it is so small, it has no interest for sport fishing.
Family: Lebiasinidae · forage fish
fun facts
- It is known from only two localities.
similar species
sources and references (3)
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.
- scientific FishBase: Nannostomus britskii (ficha da espécie)Size, length-weight, depth, habitat, distribution, biology, and IUCN status. Page checked on Oct 13, 2026.
- scientific FishBase: nomes populares de Nannostomus britskiiNames by country and language.
- 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.
how we calculatewhere each number comes from
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.
sources for this lookup
how accurate the forecast is
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: