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Acestrorhynchus falcirostris
Fishes › Tetras, piranhas and pacus (Characiformes) › Acestrorhynchidae (Freshwater barracudas)
Acestrorhynchus falcirostris is a species of freshwater ray-finned fish belonging to the family Acestrorhynchidae, the freshwater barracudas.
Care at a glance
Species-specific aquarium care
- Tank: At least 90 in long and 36 in front to back for one adult (adults commonly reach about 17.7 in / 45 cm).
- Water: Freshwater.
- Temperature: 75–82°F (range recorded for this species).
- pH: 5.2–7.2.
- Hardness: 5–18 dGH.
- Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.
- 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
- Tank: a base of at least 98 × 35 in (roughly 535 US gallons); space needed is rated “very large tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 72–82 °F, pH 6–7.5, 1–12 dGH.
- Behaviour: temperament predatory; a shoaling fish best kept in a group of six or more; not a community fish.
- Difficulty: Moderate (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “This species is a near-exclusive inhabitant of open water and an excess of cover can actually stress it, substrate aside, the majority of the tank should be décor-free with plenty of open space.”
- Diet: “An obligate piscivore capable of consuming quite large prey in relation to its body size.”
- Tankmates: “Relatively peaceful with anything too large to swallow and can be maintained in a community provided tankmates are chosen with care.”
- Breeding: “Apparently courtship and even spawning have been observed in aquaria but no fry raised.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Freshwater barracudas
Applies to most species in this group. Habitat: Acestrorhynchus inhabit South American river channels, tributaries and seasonal flooded areas, while tiny Gnathocharax occupy the upper water column in habitats also supporting cardinal tetras. [fg297-microlepis_sf, fg297-gnatho_glaser]. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- For A. microlepis and A. falcirostris, provide a tank footprint of at least 250 × 90 cm (98 × 35 inches).
- Leave most of the barracuda tank open for swimming, with sparse wood and optional sandy substrate.
- Fit a tight cover and provide substantial space even for juveniles to reduce escape and collision injuries.
- Use mature canister or sump filtration with surface movement; change 30–50% of water weekly for Acestrorhynchus.
- For Gnathocharax, the keeper reference specifies at least 80 × 30 × 40 cm, about 96 L, with floating plants, open swimming space and a cover.
Climate & lighting
| Water | 71.6–82.4°F |
Diet
- Acestrorhynchus: suitably sized fish foods; acclimate imports from live prey to dead fish where possible.
- Gnathocharax: fine flake or other small dry foods, readily accepted by imported specimens.
- Gnathocharax: live Artemia as part of a varied menu.
Social life
- Keep Acestrorhynchus in groups of four or more of comparable size; smaller companions can be swallowed. Gnathocharax are shoaling community fish; the keeper reference recommends at least eight.
Health watch
- Collision injuries in cramped barracuda tanks.
- Parasites or infections introduced with feeder fish.
- Excess fat deposition and organ damage from mammalian or avian meat.
Understanding the animal
About this animal
About this animal
It was described by Georges Cuvier in 1819, originally under the genus Hydrocyon. It inhabits the Orinoco and Amazon Rivers in the area of Guyana, at a pH range of 5.2–7.2, and a dH range of 5–18.
Quoted from the Wikipedia article “Acestrorhynchus falcirostris” (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. Found in clear and black waters. |
| Water it lives in | Freshwater, 75–82 °F (24–28 °C), pH 5.2–7.2, hardness 5–18 dH. |
| Climate | Tropical climate. |
| Wild diet | Hunting macrofauna (predator). |
What this means for care
- Keep water within its wild range, 75–82 °F.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 91°F (up to 96°F in the hottest sampled areas) |
| Cool-season lows | about 71°F (down to 66°F in the coldest sampled areas) |
| Average temperature | 78–81°F across sampled records |
| Relative humidity | 80–84% on average (driest month about 75%) |
| Rainfall | about 2319 mm a year |
Measured at 89 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 | Acestrorhynchus falcirostris is a species of freshwater ray-finned fish belonging to the family Acestrorhynchidae, the freshwater barracudas. It was described by Georges Cuvier in 1819, originally under the genus Hydrocyon. It inhabits the Orinoco and Amazon Rivers in the area of Guyana, at a pH range of 5.2–7.2, and a dH range of 5–18. It reaches a maximum standard length of 45 cm. — 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 |
| Biology | Found in clear and black waters. — 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.
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 in nature; aim for the middle.
Minimum tank footprint
Seriously Fish recommends a tank base of at least 98 × 35 in (about 535 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.
- Seriously Fish: Acestrorhynchus microlepis Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Seriously Fish: Acestrorhynchus falcirostris Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Frank Schäfer, Aquarium Glaser: Gnathocharax steindachneri Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Aquariophilie.org: Gnathocharax steindachneri Experienced keeper or breederAdded 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.