machaca
Brycon guatemalensis · Bryconidae · omnivore
A Central American relative of the matrinxã, living in rivers and lakes of the Caribbean slope. It eats fruit and seeds that fall from trees and attacks flies and small lures with jumps.
Also called: machaca
- common size
- 30–45 cm
- maximum
- 59 cm
- common weight
- 0.5–2 kg
- record/max.
- 4.3 kg
- depth
- 0–5 m
- ideal water
- 24–30 °C
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.
Reading the weather across 3 global models and 31 simulations…
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hour by hour
tap or drag on the chart to read each hour · on a keyboard, arrow keyssee hour-by-hour table
why this index at —?
choose the day
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.
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 machaca
who is the machaca
A characin of the genus Brycon, the same genus as the matrinxã and piraputanga. It lives in lowland and foothill rivers, streams and lakes up to about 600 m altitude, on the Atlantic slope of Central America, from Mexico to Panama. Juveniles eat insects, leaves, fruit and seeds; adults feed almost only on plant matter and gather under fruiting trees on the banks, such as figs. In Costa Rica and Nicaragua it is a known sport fish in lowland rivers and lagoons, where it is caught on fly and small lures imitating fruit and insects. For its size it fights with jumps and strong runs. It spawns in nests on sandy stream bottoms.
fun facts
- It swallows whole figs and spreads the seeds upstream and downstream: it is a forest seed disperser.
- Reproduction of the species in Lake Nicaragua has been studied in detail, of interest for managing local fishing.
identification
Spindle-shaped, compressed body, silvery with a greenish to olive back and fins that may have orange tones; forked tail. Medium, shiny scales, small mouth with multicuspid teeth and an adipose fin. Resembles the Brazilian matrinxã and piraputanga, which are the same genus and do not occur in Central America.
where found
Does not occur in Brazil. Atlantic (Caribbean) slope of Central America, from the Grijalva River in Mexico to eastern Panama; on the Pacific slope only in the Choluteca River basin, Honduras. Includes Lake Nicaragua and lowland rivers of Costa Rica.
Habitat: Lowland and foothill rivers and streams, lakes and lagoons; eddies under fruit trees, banks with submerged timber and rapids with rock or sand bottoms.
when to fish
best season
Fished all year. Best with low, clear water; rainy-season runoff muddies the water and scatters fish. Fruiting trees along the bank concentrate the schools.
best time of day
Daytime. Active by day, most on the move in the morning and late afternoon, when it patrols the bank for fruit and insects.
what affects the machaca
sensitivity The little bars show how much each factor affects this species. Five full: it feels it a lot.
cold and cold fronts
Colder water after heavy rain reduces activity.
atmospheric pressure
Little effect.
moon
Little effect.
rain
Runoff muddies the river and shuts fishing down for a few days.
water level
Low, clear water concentrates fish under the bankside trees.
noise
Wary in clear water; approach slowly and cast from a distance.
wind
Wind that knocks fruit and insects into the water can activate the fish.
depth
Surface and shallow mid-water, 0 to 2 m.
how to fish
- rod
- fly #5 to #7; or light spinning 6' to 7', 6 to 14 lb
- spinning / baitcasting reel
- simple fly reel or spinning reel 2000 to 3000
- line
- floating fly line; monofilament 0.22 to 0.28 mm
- leader
- fluorocarbon 10 to 15 lb
- hook
- #4 to 1/0, barbless
lures
- small popper and flies that imitate fruit and seeds
- grasshoppers and foam beetles
- spinner #2 to 3
- small spoon 5 to 10 g
natural baits
- bankside fruit (figs)
- gafanhoto
- bread
accessories
- alicate
- polarized glasses
- landing net
tip from an angler
Find trees with fruit falling into the water and cast a fruit fly just below them, letting it drift without dragging.
rules for the machaca
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: It depends on the riparian forest, which supplies much of its food.
We found no species-specific rule beyond the region's general rules.
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.
A strong fish that jumps: remove the barbless hook quickly and release it facing the current, without squeezing the body.
in the kitchen
Tasty flesh with bones, like the matrinxã. Baked or fried.
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.01023, b = 3.02; FishBase). It's an average: a fat or lean fish can vary by 10% to 20%.
estimated weight
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sources and references
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.
- scientific FishBase — Brycon guatemalensis (ficha da espécie)Names, distribution, biology, length-weight relationship, country list and references. Page checked on Oct 13, 2026.
- scientific IUCN Red List — Brycon guatemalensis (avaliação global: Pouco Preocupante, LC, 15/11/2018)Global assessment. Link given on the FishBase entry (Red List, version 2025-2).
- scientific Horn, M. H. (1997). Evidence for dispersal of fig seeds by the fruit-eating characid fish Brycon guatemalensis Regan in a Costa Rican tropical rain forest. Oecologia 109: 259-264.DOI checked in Crossref.
- scientific Hernández-Portocarrero, Domínguez-Petit e Saborido-Rey (2015). Reproductive tactics of the freshwater fish Brycon guatemalensis (Teleostei: Characidae) in Lake Nicaragua. Environmental Biology of Fishes 98: 535-546.DOI checked in Crossref.
- scientific Bussing, W. A. (1998). Peces de las aguas continentales de Costa Rica. 2ª ed. San José: Editorial de la Universidad de Costa Rica. 468 p.Printed work; the URL is the bibliographic record on FishBase, which cites this work for the species.
similar species
where 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: