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No federal permit to keepTadpole Bristlenose Catfish
Ancistrus ranunculus
Fishes › Catfish (Siluriformes) › Loricariidae (Plecos)
Ancistrus ranunculus is a species of freshwater ray-finned fish belonging to the family Loricariidae, the suckermouth armoured catfishes, and the subfamily Hypostominae, the suckermouth catfishes.
Care at a glance
Species-specific aquarium care
- Tank: At least 30 in long and 15 in front to back for one adult (adults commonly reach about 7.7 in / 19.5 cm).
- Water: Freshwater.
- Temperature: 77–82°F (range recorded for this species).
- Layout: Lives on or near the bottom: floor space and hiding places matter more than height.
- Availability: Rarely or never seen in the aquarium trade; expect to source it from specialists or not at all.
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 31 × 12 in (roughly 19 US gallons); space needed is rated “modest tank”.
- Water: soft, acidic water, 77–86 °F, pH 6–7, 2–10 dGH.
- Behaviour: temperament peaceful.
- Difficulty: Easy (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “A stream-type setup with a gravel or sand substrate and rounded stones and rocks would simulate its natural biotope, but it's equally at home in a planted tank.”
- Diet: “Prefers a more protein-rich diet than the majority of Ancistrus spp., so supplement quality, sinking dried foods with regular offerings of live and frozen foods such as bloodworm, chopped mussel, prawn and similar.”
- Tankmates: “A generally peaceful species.”
- Breeding: “Not an easy species to breed.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Plecos (suckermouth catfish)
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
- Driftwood (some species rasp it for fiber), caves and good flow.
- Common plecos reach 18–24 in; many smaller species stay under 6 in.
Diet
- Algae wafers and vegetables for herbivores; meaty foods for carnivorous species.
Health watch
- Starvation if they're expected to live on algae alone.
Understanding the animal
About this animal
About this animal
This catfish is found in Colombia and Venezuela.
Quoted from the Wikipedia article “Ancistrus ranunculus” (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. Stays near the bottom. Inhabits clear running water, without a strong current to a depth of 3 meters during dry season. Prefers narrow cracks of submerged rocks, small passages between superimposed rocks, or lives below flat rocks on the bottom. |
| Water it lives in | Freshwater, 77–82 °F (25–28 °C). |
| Climate | Subtropical climate. |
What this means for care
- Keep water within its wild range, 77–82 °F.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 90°F (up to 91°F in the hottest sampled areas) |
| Cool-season lows | about 67°F (down to 65°F in the coldest sampled areas) |
| Average temperature | 77–79°F across sampled records |
| Relative humidity | 83–85% on average (driest month about 76%) |
| Rainfall | about 1971 mm a year |
Measured at 93 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 | Ancistrus ranunculus is a species of freshwater ray-finned fish belonging to the family Loricariidae, the suckermouth armoured catfishes, and the subfamily Hypostominae, the suckermouth catfishes. This catfish is found in Colombia and Venezuela. — 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 |
| Appearance and size | Ancistrus ranunculus reaches a standard length of 19.5 cm and a weight of 153.7 g. Ancistrus species develop soft, bushy tentacles on the snout when sexually mature, these are better developed in the males than they are in females. — Wikipedia (community-edited) |
| Biology | Facultative or obligate air-breathing; Inhabits clear running water, without a strong current to a depth of 3 meters during dry season. Prefers narrow cracks of submerged rocks, small passages between superimposed rocks, or lives below flat rocks on the bottom. — FishBase |
| History and naming | Ancistrus ranunculus was first formally described in 2016 by the ichthyologists Sonia Fisch-Muller, who is Swiss, Alexandre Rodrigues Cardoso, José Francisco Pezzi da Silva and Vinicius de Araújo Bertaco, who are Brazilian, with its type locality given as the Xingu River at furo do Tucum Seco, near Arroz Cru, in the Brazilian state of Pará. — Wikipedia (community-edited) |
| Conservation | Ancistrus ranunculus is classified ar Near Threatened by the IUCN. The main threat to this species are a number of proposed hydroelectric dams that affect most of the river ssytems this species occurs in. — Wikipedia (community-edited) |
Data and studies
Researched care notes
Researched care notes
Findings checked against veterinary, zoo, welfare, keeper and peer-reviewed sources. Air, basking-surface and water temperatures are kept separate, and where sources disagree both are shown. “Study” notes report what a paper measured, not a universal rule.
Bristlenose Pleco
Researched for this genus; applies to its species unless a species note says otherwise.
- The common aquarium bristlenose has uncertain ancestry; do not automatically identify every trade specimen as confirmed Ancistrus cirrhosus.1
- For the common trade bristlenose profile, Seriously Fish gives water temperature 21–26°C, pH 5.5–7.5 and hardness 1–15 dGH.1
- Provide well-oxygenated water and plentiful cover rather than treating the fish as a substitute for aquarium maintenance.1
- Bristlenoses can be territorial toward conspecifics and similarly shaped fish; a peaceful community reputation does not guarantee compatibility between males.1
- Offer dedicated sinking foods with vegetable components and other appropriate variety; the source does not present incidental algae alone as a complete ration.1
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.
pH
Water hardness
Minimum tank footprint
Seriously Fish recommends a tank base of at least 31 × 12 in (about 19 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.
- Seriously Fish — Ancistrus sp. “3” / common bristlenose identification 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.
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