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No federal permit to keepRipsaw catfish
Oxydoras niger
Fishes › Catfish (Siluriformes) › Doradidae (Thorny catfish)
Oxydoras niger, commonly known as the ripsaw catfish or cuiu cuiu, is a species of thorny catfish native to the Amazon, Essequibo, and São Francisco river basins in Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru and Venezuela.
Care at a glance
Species-specific aquarium care
- Tank: At least 90 in long and 45 in front to back for one adult (adults commonly reach about 23.2 in / 59 cm; the largest recorded was 39.4 in).
- Water: Freshwater.
- Temperature: 70–75°F (range recorded for this species).
- pH: 6–7.8.
- Hardness: 0–25 dGH.
- Layout: Lives on or near the bottom: floor space and hiding places matter more than height.
- 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.
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 94 × 24 in (roughly 457 US gallons); space needed is rated “very large tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, pH 6–7, 0–20 dGH.
- Difficulty: Not enough data to rate (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “Will appreciate cover in the form of rockwork, roots and bogwood.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Thorny catfish
Applies to most species in this group. Habitat: South American doradids include nocturnal Raphael catfish sheltering among roots and vegetation in sluggish tributaries, creeks and swamps. [fg181-raph]. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- For Platydoras armatulus, provide at least 120 × 30 × 30 cm; this minimum does not house giant doradids.
- Use subdued lighting and numerous roomy wood, pot or pipe refuges.
- Deliver sinking food after lights-out to reach hidden fish.
- Oxydoras niger needs very large accommodation and adult-sized drainpipe or wood shelters.
- Guard heaters against resting fish, particularly large Oxydoras.
Climate & lighting
| Water | 75.2–86°F |
Diet
- Sinking catfish pellets or tablets.
- Frozen bloodworms.
- Earthworms.
- Chopped mussel for larger Oxydoras.
Social life
- Platydoras armatulus tolerates its own kind and may share shelters; Oxydoras is also generally peaceful. Choose companions too large to swallow.
Handling
- Avoid mesh entanglement when transferring spiny doradids; protect yourself from sharp pectoral spines and lateral scutes.
Health watch
- Heater-contact burns in large sheltering catfish.
- Ammonia-related gill injury in poorly maintained systems.
- Skin parasites and secondary bacterial infections; general aquarium-fish risks.
Understanding the animal
About this animal
About this animal
It is the largest member of the family Doradidae. It grows up to a length of 100 centimetres (3 ft 3 in) and weighs up to 13 kilograms (29 lb).
Quoted from the Wikipedia article “Oxydoras niger” (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. Stays near the bottom. Occurs over mud in streams and lakes. Forms schools. |
| Water it lives in | Freshwater, 70–75 °F (21–24 °C), pH 6–7.8, hardness 25 dH. |
| Climate | Tropical climate. |
| Wild diet | Hunting macrofauna (predator). |
What this means for care
- Keep water within its wild range, 70–75 °F.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 91°F (up to 93°F in the hottest sampled areas) |
| Cool-season lows | about 69°F (down to 61°F in the coldest sampled areas) |
| Average temperature | 77–81°F across sampled records |
| Relative humidity | 76–84% on average (driest month about 75%) |
| Rainfall | about 2120 mm a year |
Measured at 182 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 | Oxydoras niger, commonly known as the ripsaw catfish or cuiu, is a species of thorny catfish native to the Amazon, Essequibo, and São Francisco river basins in Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru and Venezuela. It is the largest member of the family Doradidae. It grows up to a length of 100 cm and weighs up to 13 kg. The species forms a minor part of local commercial fisheries. — 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 | These catfish eat crustaceans, snails, and other inverebrates, seeds, and fruits (Sands, 1997). — Animal Diversity Web |
| Behavior | Pseudodoras niger engage in an annual fish run known as the piracema. — Animal Diversity Web |
| Reproduction | No information could be found regarding the breeding of this animal, except that inferred from its migration pattern (see 'Behavior'). — Animal Diversity Web |
| Appearance and size | Maximum length 100.0 cm sl male/unsexed; maximum published weight 11.0 kg. — FishBase |
| Biology | Adults occur over mud in streams and lakes. They form schools and feed on detritus, chironomid and ephemeropteran larvae, and crustaceans. Known from temperatures ranging from 24-29.8 °C, pH range of 5-9, and an alkalinity range of 42-142. — FishBase |
| Conservation | O. niger is listed as Least Concern by the IUCN Red List. It is used in local fisheries and is also present in the aquarium trade. The species may be affected by broader human pressures on Amazonian freshwater habitats, including river development and dam construction. — 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
Common length to 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.
Water hardness
Minimum tank footprint
Seriously Fish recommends a tank base of at least 94 × 24 in (about 457 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: Platydoras armatulus Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- ScotCat: Oxydoras niger factsheet Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Merck Veterinary Manual: Disorders and Diseases of Fish 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.
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