Home / Fishes / Tetras, piranhas and pacus / Redhook myleus
No federal permit to keepRedhook myleus
Myloplus rubripinnis
Fishes › Tetras, piranhas and pacus (Characiformes) › Serrasalmidae (Piranhas and pacus)
The redhook myleus or redhook silver dollar (Myloplus rubripinnis) is a medium-sized omnivorous fish in the family Serrasalmidae.
Care at a glance
Species-specific aquarium care
- Tank: At least 84 in long and 33 in front to back for one adult (adults commonly reach about 16.3 in / 41.5 cm).
- Water: Freshwater.
- Temperature: 73–81°F (range recorded for this species).
- pH: 5–7.
- Hardness: 0–15 dGH.
- Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.
- Diet: FishBase classes it as a herbivore.
- Safety: Can injure people (sharp spines, teeth or electric shock): use nets and care when working in the tank.
Calculated from this species' own FishBase record: tank size from its typical adult length and swimming zone, water values from its recorded ranges. The group guide below fills in general care.
Care guide
Species care notes
- Tank: a base of at least 71 × 15 in (roughly 69 US gallons); space needed is rated “very large tank”.
- Water: soft, acidic water, 73–81 °F, pH 6–7, 0–10 dGH.
- Behaviour: temperament predatory; a shoaling fish best kept in a group of six or more.
- Difficulty: Difficult (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “Inhabits densely planted river tributaries in the wild.”
- Diet: “A herbivorous species, in nature it feeds chiefly on the leaves of submerged or marginal vegetation, including terrestrial plants.”
- Tankmates: “Best kept in groups of at least five fish.”
- Breeding: “Not achieved in the hobby.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Piranhas, pacus and silver dollars
Applies to most species in this group. Habitat: South American rivers. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- Large tanks with strong filtration; pacus grow to over 2 ft and outgrow almost every home aquarium.
Diet
- Silver dollars: plant-based foods. Piranhas: fish, shrimp and pellets.
Health watch
- Piranhas are banned in many states. Never release pacus.
Understanding the animal
About this animal
About this animal
It is from South America, where it is found in the Amazon and Orinoco basins, as well as rivers of the Guiana Shield. This species schools often and is peaceful; despite that, it is capable of delivering serious bites to humans.
Quoted from the Wikipedia article “Redhook myleus” (CC BY-SA 4.0) 174
In the wild
In the wild
From this species’ own FishBase record (habitat, bottom type, water and breeding data), not its family. Good care copies these conditions.1
| Where it lives | Lives in freshwater, in rivers and streams. Uses both the bottom and open water. |
| Water it lives in | Freshwater, 73–81 °F (23–27 °C), pH 5–7, hardness 15 dH. |
| Climate | Tropical climate. |
| Wild diet | Other. |
| Behavior to plan for | Breeding: open water/substratum egg scatterers. |
What this means for care
- Keep water within its wild range, 73–81 °F.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 91°F (up to 95°F in the hottest sampled areas) |
| Cool-season lows | about 69°F (down to 62°F in the coldest sampled areas) |
| Average temperature | 77–81°F across sampled records |
| Relative humidity | 78–83% on average (driest month about 73%) |
| Rainfall | about 2216 mm a year |
Measured at 305 wild occurrence records sampled against WorldClim 2.1 climate data (1970–2000 averages). Air conditions in the range are ecological context, not enclosure settings: microhabitats such as burrows, leaf litter or basking rocks can be cooler, warmer or more humid.
From the sources
From the sources
Quoted from the matching sections of reputable sources for this exact species. Specialist databases are used first; Wikipedia (community-edited, CC BY-SA 4.0) only fills gaps. Other sources are short credited quotes.
| Overview | The redhook myleus or redhook silver dollar (Myloplus rubripinnis) is a medium-sized omnivorous fish in the family Serrasalmidae. It is from South America, where it is found in the Amazon and Orinoco basins, as well as rivers of the Guiana Shield. This species schools often and is peaceful; despite that, it is capable of delivering serious bites to humans. — Wikipedia (community-edited) |
| Where it lives | Home ranges Population dynamics Growth parameters Max. ages / sizes Length-weight rel. Length-frequencies Mass conversion Recruitment Abundance Life cycle Reproduction Maturity Maturity/Gills rel. — FishBase |
| Reproduction | The red hooked anal fin of the female is actually a plough. The male has a bilobed anal fin which is designed to wrap around the female's "hook". During spawning, the female inserts the hook into the substrate (e.g., gravel) and ploughs a furrow while laying the eggs with the male in a position next to her with his bi-lobed fin wrapped around the hook as he fertilises the eggs. — FishBase |
| Biology | Gregarious and non-aggressive. Individuals prefer calm zones of main rivers where the vegetation hangs over the river banks. Migratory behaviour is undetermined. — FishBase |
| History and naming | Both the term "redhook" in the common name and the specific epithet are references to the fact that the anal fin of this fish is (largely) red. — Wikipedia (community-edited) |
Data and studies
The numbers
The numbers
Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.
Typical adult weight
Average adult body mass in each database (FishBase gives the maximum recorded weight).
Adult length
Maximum recorded length. Measured as total length. Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates in nature; aim for the middle.
Water hardness
Minimum tank footprint
Seriously Fish recommends a tank base of at least 71 × 15 in (about 69 US gallons).
Sources for this sheet
- FishBase (Froese & Pauly, eds.), version 24.07 Peer-reviewed researchThe global scientific database on fishes, maintained by a consortium of research institutions; every value is referenced.
- Seriously Fish species profiles Experienced keeper or breederLong-running aquarium reference written and peer-checked by experienced fishkeepers and ichthyologists; each profile covers habitat, tank size, water, diet, behaviour and breeding.
- Merck Veterinary Manual: Management of aquarium fish Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
- Merck Veterinary Manual: Types and features of aquatic systems Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
- Merck Veterinary Manual: Nutritional diseases of fish Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
- Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
- iNaturalist (captive observations) Community referenceCommunity observation platform run by the California Academy of Sciences and National Geographic; observations marked captive show animals living in homes, zoos and aquariums.
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