reef butterflyfish
Chaetodon sedentarius · Chaetodontidae · omnivore
Butterflyfish of Caribbean and Brazilian reefs, with a wide dark band on the tail peduncle. There are reports of ciguatera, so it is not a fish to eat. It is used in aquariums.
Also called: borboleta-de-recife, isabelita negra, mariposa parche, reef butterflyfish
- maximum
- 15 cm
- depth
- 15–40 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
slide your finger or mouse over the chart to see each hoursee 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 reef butterflyfish
who is the reef butterflyfish
Butterflyfish of the family Chaetodontidae, living on coral reefs. It reaches 15 cm, and reproduction begins at about 8 cm. It ranges from North Carolina, USA, to northern South America, including the eastern Gulf of Mexico and the Caribbean. It lives between 5 and 92 m, but usually stays between 15 and 40 m. It likes to eat sergeant major eggs, but also eats polychaete worms, shrimp, amphipods and hydroids. It pairs up for breeding and lays eggs in the water. In fishing it is bycatch, and it has aquarium value.
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 reef butterflyfish; in the meantime, see the similar species.
fun facts
- It prefers to eat the eggs of the sergeant major (Abudefduf saxatilis), a reef fish.
identification
Scales with yellowish edges on the back, a black bar on the head running through the eye, and a wide dark bar on the tail peduncle that extends into the soft parts of the dorsal and anal fins. The caudal fin is pale yellow, with a white base. To tell it apart from Chaetodon ocellatus, look at the wide tail bar: ocellatus has yellow or transparent fins and a yellow band at the level of the pectoral fin.
where found
In Latin America it occurs on reefs of Mexico, Cuba, Venezuela and Brazil, in the Gulf of Mexico and the Caribbean.
Habitat: Coral reefs, usually 15 to 40 m.
coast
rules for the reef butterflyfish
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.
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.
There are no reports of danger from touching it, but there are reports of ciguatera, so it is not a fish to eat. Handle it with a wet hand and release it quickly.
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.02344, b = 3.02; 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: Chaetodon sedentarius (ficha da espécie)Size, length-weight, depth, habitat, distribution, biology, and IUCN status. Page checked on Oct 13, 2026.
- scientific FishBase: nomes populares de Chaetodon sedentariusNames 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.
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: