Home / Fishes / Tetras, piranhas and pacus / Biara
No federal permit to keepBiara
Rhaphiodon vulpinus
Fishes › Tetras, piranhas and pacus (Characiformes) › Cynodontidae (Payara and dogtooth characins)
The biara (Rhaphiodon vulpinus), also known at Machete Payara is a South American piscivorous fish in the dogtooth characin family.
Care at a glance
Species-specific aquarium care
- Tank: At least 192 in long and 63 in front to back for one adult (adults commonly reach about 31.5 in / 80 cm).
- Water: Freshwater.
- Layout: An open-water swimmer: needs long, open swimming space with few obstacles.
- Diet: A predator: feed meaty foods sized to its mouth (frozen fish, shrimp, worms); it will eat tankmates that fit in its mouth. FishBase classes it as a carnivore.
- Availability: Mostly kept by public aquariums; private keeping is uncommon.
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
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 75–82 °F, pH 6–8, 2–15 dGH.
- Behaviour: kept alone; not a community fish.
- Difficulty: Moderate (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “The aquarium should ideally be designed to resemble a flowing stream or river with a substrate of variably-sized rocks, sand, fine gravel, and some larger water-worn boulders.”
- Diet: “An obligate but generalised piscivore capable of consuming surprisingly large prey.”
- Tankmates: “Best kept alone, or with similarly-sized, non-aggressive fishes it cannot fit into its mouth since it's otherwise quite peaceful and easily-dominated.”
- Breeding: “This species is reproductively active between the months of September/October to January/April, this period coinciding with high water levels across much of its range.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Tetras and other characins
Applies to most species in this group. Habitat: Soft, tea-colored rivers and streams. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- Planted tanks with subdued light; many prefer soft, slightly acidic water.
- Schools of six or more (more is better); hatchetfish need tight lids.
Diet
- Small community tetras can use appropriately sized prepared and invertebrate foods; this is not a diet for every characin. Adult Hoplias malabaricus is a fish predator and needs a separate feeding guide.
Social life
- Schooling fish.
Health watch
- Stress and ich if water swings or schools are too small.
Understanding the animal
About this animal
About this animal
It belongs to the monotypic genus Rhaphiodon, although some minor differences in morphometrics and colour are known from across its large range. It is found in the Amazon, Orinoco, and Río de la Plata Basins, as well as rivers of the Guianas.
Quoted from the Wikipedia article “Biara” (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. Apparently carnivorous, probably ichthyophagous. Maximum length reported to reach 64 cm SL. |
| Water it lives in | Freshwater. |
| Climate | Tropical climate. |
| Wild diet | Hunting macrofauna (predator). |
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 90°F (up to 94°F in the hottest sampled areas) |
| Cool-season lows | about 67°F (down to 54°F in the coldest sampled areas) |
| Average temperature | 73–81°F across sampled records |
| Relative humidity | 74–83% on average (driest month about 71%) |
| Rainfall | about 1928 mm a year |
Measured at 399 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 biara (Rhaphiodon vulpinus), also known at Machete Payara is a South American piscivorous fish in the dogtooth characin family. It belongs to the monotypic genus Rhaphiodon, although some minor differences in morphometrics and colour are known from across its large range. It is found in the Amazon, Orinoco, and Río de la Plata Basins, as well as rivers of the Guianas. It occurs in a wide range of freshwater habitats such as main river channels, flooded forests, lakes and reservoirs. — 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 |
| Wild diet | Like its relatives, the biara feeds almost entirely on other fish, which are speared by the long canines. In a study of the stomach content of 100 biaras, the majority were empty. The remaining had prey fish that were 30–50% of the length of the biara itself, and only a single contained another prey type, a mayfly larvae. — Wikipedia (community-edited) |
| Reproduction | In a study observing the reproductive biology of the biara species in the Tocantins River of Brazil, it was found that the prime reproductive period takes place in November. The high-water conditions of the environment correlate to the increase of reproductive rate. — Wikipedia (community-edited) |
| Appearance and size | Maximum length 80.0 cm sl male/unsexed; maximum published weight 2.1 kg. — FishBase |
| Biology | Apparently carnivorous, probably ichthyophagous. Maximum length reported to reach 64 cm SL. — FishBase |
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 standard length (snout to the base of the tail, not counting the tail fin). Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates; aim for the middle.
pH
Water hardness
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.
- Seasonal diet shifts of seven fish species in an Atlantic rainforest stream in Southeastern Brazil (2003) Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Seriously Fish — Paracheirodon innesi Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- 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.
