convict surgeonfish
Acanthurus triostegus · Acanthuridae · omnivore
Shallow-reef surgeonfish, with a sharp cutting spine on each side of the tail stalk. It is almost never caught on rod, but it appears in reef catches, and there are reports of ciguatera.
Also called: cirurgião-presidiário, cirujano convicto, convict surgeonfish
- maximum
- 27 cm
- depth
- 0–90 m
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 convict surgeonfish
who is the convict surgeonfish
Fish of the surgeonfish family (Acanthuridae), with a flattened, disk-shaped body, reaching 27 cm. It lives on reefs and lagoons with hard bottoms, from the tidal zone down to 90 m. In the Pacific Americas it occurs from the Gulf of California to Panama, with records at the Revillagigedo, Cocos and Galápagos islands. Juveniles are common in tide pools. Adults scrape filamentous algae from rocks and, during spawning, form large aggregations. It is rarely the target of rod fishing. It is used as a food fish in some places and sold for aquariums.
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 convict surgeonfish; in the meantime, see the similar species.
fun facts
- During spawning they form aggregations, and eagle rays are often nearby, feeding on the clouds of eggs and sperm.
identification
Grayish-olive body, lighter on the belly, with dark vertical bands: one on the head, passing through the yellow eye, and another on the tail stalk. It has a sharp, movable spine on each side of the stalk, which folds into a groove. The teeth are serrated at the sides and the scales are very small. Because of the bands and the yellow eye, it is easy to tell it apart from the black surgeonfish, which is almost entirely dark.
where found
In the Pacific Americas, from the reefs of Mexico to Colombia, including Central America and the Revillagigedo, Cocos and Galápagos islands.
Habitat: Reefs and lagoons with hard bottoms, from the tidal zone down to 90 m.
rules for the convict surgeonfish
Summary of the regulations we found, with the source for each. 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.
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 has a movable, sharp spine on each side of the tail stalk, which can wound anyone who handles it. Hold it carefully and avoid touching that area.
in the kitchen
Used as a food fish, but there are reports of ciguatera: avoid eating specimens of doubtful origin.
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.02344, b = 2.97; FishBase (relação peso-comprimento bayesiana, estimativa da própria espécie)). 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.
- scientific FishBase: Acanthurus triostegus (ficha da espécie)Size, length-weight, depth, habitat, distribution, biology, and IUCN status. Page checked on Oct 13, 2026.
- scientific FishBase: nomes populares de Acanthurus triostegusNames by country and language.
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: