Silvery pacu with a red anal fin with a black edge, from calm waters with vegetation over the bank. It eats leaves of river plants, moves in shoals and bites hard.
Medium-sized, disc-shaped pacu that lives in shoals in the calm parts of large rivers, where vegetation hangs over the bank. According to FishBase, it is gregarious and not very aggressive, but has powerful teeth capable of serious bites; adults eat leaves of river plants. The red anal fin, hook-shaped in adults (hence 'redhook' in English), plays a role in spawning: the female uses it to dig a furrow in the gravel while the male wraps his bilobed anal fin around her. It reaches 41.5 cm and 2.5 kg and has a minor commercial fishery. Taxonomy is complex: Myloplus rubripinnis and M. asterias are very similar, and recent research restricts M. rubripinnis to the Guiana Shield, treating the pacu of Brazilian Amazonia under that name as a possible undescribed species.
fun facts
The female's red anal fin works like a plow: she digs a furrow in the gravel while releasing eggs, and the male wraps his bilobed anal fin around the hook-shaped part (FishBase).
The species was described from Guyana, and the Amazonian populations may be a different species (Ota et al., 2020).
how to recognize it
identification
Tall, disc-shaped, silvery pacu with a red anal fin with a black edge, which in adults is hook-shaped. Small head, serrated keel on the belly and strong crushing teeth. It lacks the vertical black bar of the pacu-cadete (Myloplus schomburgkii) and the black spot on the gill cover of the pacu-peva (Mylossoma duriventre). Telling M. rubripinnis from M. asterias uses dorsal fin rays and the shape of the fontanelle, and is not done in the field.
how redhook myleus fishing looks
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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.
Amazon and Orinoco basins and rivers of the Guiana Shield. In Brazil, M. rubripinnis in the strict sense occurs in the rivers of the Guiana Shield (Araguari, Jari, Oiapoque); populations of Brazilian Amazonia, such as those of the Tapajós, previously called by this name, are now treated as a possible undescribed species (Ota et al., 2020).
Habitat: Calm parts of large rivers, where vegetation hangs over the bank; also tributaries with dense vegetation (estimate based on the leaf-eating habit of pacus).
native to the basins
Amazon
states
Amapá, Pará, Amazonas
calendar and clock
when to fish
best season
time of yearbest: Jul–Nov
JanFebSeaAprMayJunJulAugSepOctNovDec
Estimate: falling water and dry season concentrate shoals in eddies with vegetation. At high water the fish spreads through the flooded forest.
best time of day
Daytime. No timing studies. Like pacus in general, it feeds by day (estimate).
weather, water and behavior
what affects the redhook myleus
sensitivity The little bars show how much each factor affects this species. Five full: it feels it a lot.
cold and cold fronts
Cold snaps (friagem) shut down activity for a few days.
atmospheric pressure
Stable pressure helps.
moon
Little known effect.
rain
Light rain doesn't bother it.
water level
A falling river concentrates the shoal under the vegetation.
noise
Seriously Fish describes it as somewhat nervous: approach quietly.
bamboo pole 3 to 4 m or rod 5'6" to 6', 8 to 15 lb
spinning / baitcasting reel
spinning reel 1000 to 2500
line
monofilament 0.25 to 0.30 mm
leader
fluorocarbon 30 lb, 30 cm: the teeth cut thin line
hook
No. 2 to 1/0, strong, short shank
natural baits
fruit and leaves from the bank
boiled corn
flour dough
accessories
small float
long-nose pliers
tip from an angler
Plant bait on the float, right against the vegetation hanging over the water (estimate based on its leaf-eating habit). Set the hook fast and use a leader: the bite hurts.
what the law says
rules for the redhook myleus
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).
PA and AP: the portaria cites 'pacu (Myleus spp.)' in the closed season
fishing banned Nov 15 to Mar 15 for 'pacu (Myleus spp.)'; application to the genus Myloplus not confirmed15/11 to 15/03PAAPAmazonconfirm with the agency
The portaria bans fishing for 'pacu (Myleus spp. and Mylossoma spp.)' in PA and AP, from Nov 15 to Mar 15. Myloplus are not named and have already been classified as Myleus; applying the ban to them depends on the agency's interpretation. Under art. 2º, II, the recreational angler using handline or rod is exempt, unless a stricter state rule applies. When in doubt, check with the state agency.
piracema closures in the basins where the species lives
Spawning closure (piracema) in Mato Grosso (all basins)
01/10 to 31/01MT
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: 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.
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.
Hold it from below, with a damp cloth and away from the mouth: the teeth crush and cut. Remove the hook with long-nose pliers and return the fish to the water.
in the kitchen
FishBase lists it as a minor commercial fishery species. Pacu meat, good baked or fried; we found no market notes specific to the species.
calculator
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
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.
scientificFishBase: Myloplus rubripinnis (ficha da espécie)Size, length-weight relationship, depth, habitat, distribution, biology and IUCN status. Page checked on October 13, 2026. The maximum weight of 2.5 kg is the one published in FishBase; the common sizes and weights on this card are editorial estimates, calculated from the length-weight relationship.
technicalSeriously Fish: Myloplus rubripinnisRed anal fin with a black edge, herbivorous and shoaling habit, slow rivers with dense vegetation. Page checked on October 13, 2026.
