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No federal permit to keepAmazon puffer
Colomesus asellus
Fishes › Pufferfish (Tetraodontiformes) › Tetraodontidae (Pufferfish)
Colomesus asellus, the Amazon puffer, asellus puffer, South American freshwater puffer, Peruvian puffer, or Brazilian puffer is a species of pufferfish confined to the Amazon, Essequibo and Orinoco basins in tropical South America.
Care at a glance
Species-specific aquarium care
- Tank: At least 24 in long and 12 in front to back for one adult (adults commonly reach about 5.0 in / 12.8 cm).
- Water: Freshwater.
- Temperature: 72–82°F (range recorded for this species).
- pH: 5.5–7.2.
- Hardness: 5–15 dGH.
- Layout: Lives on or near the bottom: floor space and hiding places matter more than height.
- Diet: 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 47 × 12 in (roughly 29 US gallons); space needed is rated “large tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 68–79 °F, pH 5.5–8, 2–15 dGH.
- Behaviour: 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: “Choice of décor is not especially critical though it should be maintained in a well-decorated set-up.”
- Diet: “Tetraodontids lack true teeth, the jawbone itself being modified into four fused toothlike structures.”
- Tankmates: “Not aggressive as such but unsuitable for the general community aquarium, and best-maintained alone or in a larger set-up with other fluvial fishes.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Pufferfish
Applies to most species in this group. Habitat: Pufferfish inhabit marine reefs and coastal waters, brackish estuaries and, in some lineages, freshwater rivers and lakes. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- Identify species and salinity needs before setup: Tetraodon mbu needs freshwater, Arothron and Canthigaster need marine systems, and green-spotted puffers need a separate salinity plan.
- For adult T. mbu, the cited profile specifies about 240 × 90 × 90 cm (96 × 36 × 36 in), approximately 1,944 litres.
- Marine Canthigaster require around 150 litres; Arothron meleagris require an absolute minimum around 500 litres, preferably twice that; giant species require larger facilities.
- Provide strong biological filtration and regular waste removal; large marine puffers also require effective mechanical filtration and protein skimming.
- Provide rocks, caves and open swimming room, and protect cables and breakable equipment from their beaks.
Climate & lighting
| Water | 75–79°F |
Diet
- Snails and hard-shelled molluscs such as mussels or cockles for shell-crushing species.
- Shell-on crustaceans or crab legs sized to the fish.
- For Canthigaster, small portions of chopped prawn, frozen Mysis and algal foods.
Social life
- Keep T. mbu alone: it can severely injure other fish and is aggressive to conspecifics. Marine tobies commonly nip trailing fins; puffers can consume aquarium invertebrates. Assess compatibility by species and individual.
Handling
- Never deliberately induce inflation.
- Keep fingers and vulnerable equipment away from the beak.
Health watch
- Overgrown teeth interfering with feeding.
- Overfeeding and diet-related health problems.
- Water-quality illness associated with heavy waste production.
Understanding the animal
About this animal
About this animal
It is a popular aquarium species. It has typically been recognized as the only true freshwater pufferfish of South America, but a study in 2013 recommended that the population in the Tocantins River basin (quite similar to C. asellus in appearance, but differs in genetics) should be considered as a separate species, C. tocantinensis.
Quoted from the Wikipedia article “Colomesus asellus” (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. Found mostly in freshwater and coastal streams, but can tolerate brackish water. Sometimes kept in aquariums. |
| Water it lives in | Freshwater, 72–82 °F (22–28 °C), pH 5.5–7.2, hardness 5–15 dH. |
| Climate | Tropical climate. |
What this means for care
- Keep water within its wild range, 72–82 °F.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 90°F (up to 92°F in the hottest sampled areas) |
| Cool-season lows | about 70°F (down to 64°F in the coldest sampled areas) |
| Average temperature | 78–81°F across sampled records |
| Relative humidity | 81–84% on average (driest month about 77%) |
| Rainfall | about 2212 mm a year |
Measured at 214 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 | Colomesus asellus, the Amazon puffer, asellus puffer, South American freshwater puffer, Peruvian puffer, or Brazilian puffer is a species of pufferfish confined to the Amazon, Essequibo and Orinoco basins in tropical South America. It is a popular aquarium species. It has typically been recognized as the only true freshwater pufferfish of South America, but a study in 2013 recommended that the population in the Tocantins River basin (quite similar to C. asellus in appearance, but differs in genetics) should be considered as a separate species, C. tocantinensis. — 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 | The coloration of this fish is green above, white below, and patterned with black transverse bands across the dorsal surface. Compared with Colomesus psittacus, the black bands on the back are much thicker, and it also has a distinctive black band that rings the base of the caudal fin. This species grows to a length of 12.8 cm SL. — Wikipedia (community-edited) |
| Biology | Found mostly in freshwater and coastal streams, but can tolerate brackish water. Sometimes kept in aquariums. — 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 47 × 12 in (about 29 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 — tetraodon mbu Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Seriously Fish — tetraodon nigroviridis Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Practical Fishkeeping — Marine puffer fish: The inflation great! Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Practical Fishkeeping — Pufferfish: Inflated egotists Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Natural History Museum — Pufferfish: An underwater balloon of death? 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.
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