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No federal permit to keepCachama
Colossoma macropomum
Fishes › Tetras, piranhas and pacus (Characiformes) › Serrasalmidae (Piranhas and pacus)
The tambaqui (Colossoma macropomum) is a large species of freshwater fish in the family Serrasalmidae.
Care at a glance
Species-specific aquarium care
- Tank: At least 138 in long and 54 in front to back for one adult (adults commonly reach about 27.6 in / 70 cm; the largest recorded was 42.5 in).
- Water: Freshwater.
- Temperature: 72–82°F (range recorded for this species).
- pH: 5–7.8.
- Hardness: 0–20 dGH.
- Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.
- Diet: A grazer on plants and algae: base the diet on vegetable foods (algae wafers, blanched vegetables, spirulina). FishBase classes it as a herbivore.
- Safety: Can injure people (sharp spines, teeth or electric shock): use nets and care when working in the tank.
- 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 118 × 35 in (roughly 642 US gallons); space needed is rated “very large tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 72–82 °F, pH 5.5–7.5, 1–15 dGH.
- Behaviour: temperament peaceful; a shoaling fish best kept in a group of six or more.
- Difficulty: Moderate (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “The size of the tank and filtration used are much more important than the choice of decor.”
- Diet: “Stomach analyses of wild specimens show it to be primarily a herbivorous species, feeding on fruits, nuts and seeds.”
- Tankmates: “Small fish will likely be eaten, but in general it's quite peaceful with bigger species.”
- Breeding: “Not achieved in the hobby, although it's being bred in some numbers for food in both South America and various Far Eastern countries.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Piranhas, pacus and silver dollars
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
- Large tanks with strong filtration; pacus grow to over 2 ft and outgrow almost every home aquarium.
Diet
- Silver dollars: plant-based foods. Piranhas: fish, shrimp and pellets.
Health watch
- Piranhas are banned in many states. Never release pacus.
Understanding the animal
About this animal
About this animal
It is native to tropical South America, but kept in aquaculture and introduced elsewhere. It is also known by the names black pacu, black-finned pacu, giant pacu, cachama, gamitana, and sometimes as pacu (a name used for several other related species).
Quoted from the Wikipedia article “Tambaqui” (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. This species is usually solitary. Adults stay in flooded forests during first 5 months of flooding and consume but fruits and grains. Young and juveniles live in black waters of flood plains until their sexual maturity. Feeds on zooplankton, insects, snails and decaying plants. |
| Water it lives in | Freshwater, 72–82 °F (22–28 °C), pH 5–7.8, hardness 20 dH. |
| Climate | Tropical climate. |
| Wild diet | Grazing on aquatic plants. |
| Behavior to plan for | Breeding: open water/substratum egg scatterers. |
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 94°F in the hottest sampled areas) |
| Cool-season lows | about 69°F (down to 60°F in the coldest sampled areas) |
| Average temperature | 76–81°F across sampled records |
| Relative humidity | 77–84% on average (driest month about 75%) |
| Rainfall | about 2203 mm a year |
Measured at 231 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 tambaqui (Colossoma macropomum) is a large species of freshwater fish in the family Serrasalmidae. It is native to tropical South America, but kept in aquaculture and introduced elsewhere. It is also known by the names black pacu, black-finned pacu, giant pacu, cachama, gamitana, and sometimes as pacu (a name used for several other related species). The tambaqui is currently the only member of Colossoma, but the Piaractus species were also included in this genus in the past. — 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 | Tambaqui consume fruits and seeds, especially from woody angiosperms and herbaceous species. Depending on the quantity and food quality of these foods, it causes the fish to decide on their location of their habitat. In one study during the high-water season, 78—98 percent of the diet consisted of fruits. — Wikipedia (community-edited) |
| Reproduction | This species is mostly solitary, but it migrates in large schools. During the non-breeding season, adults stay in flooded forests of white (várzea), clear and blackwater (igapó) rivers. They stay there for four to seven months during the flood season, but as the water level drops they move into the main river channels or to a lesser extent floodplain lakes. — Wikipedia (community-edited) |
| Appearance and size | Maximum length 108 cm tl male/unsexed; maximum published weight 40.0 kg. — FishBase |
| Biology | This species is usually solitary. Adults stay in flooded forests during first 5 months of flooding and consume but fruits and grains. Young and juveniles live in black waters of flood plains until their sexual maturity. — 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
Common length to 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.
Water hardness
Minimum tank footprint
Seriously Fish recommends a tank base of at least 118 × 35 in (about 642 US gallons).
Veterinary & husbandry research
Veterinary & husbandry research
- Colossoma macropomum-A tropical fish model for biology and aquaculture Val AL et al., Journal of experimental zoology. Part A, Ecological and integrative physiology 2021
- Extreme climate scenario and parasitism affect the Amazonian fish Colossoma macropomum da Costa JC et al., The Science of the total environment 2020
- Development of microsatellite markers using next-generation sequencing for the fish Colossoma macropomum Ariede RB et al., Molecular biology reports 2018
- Growth and hematological responses of tambaqui, Colossoma macropomum fed different levels of rice, Oryza spp Aride PHR et al., Brazilian journal of biology = Revista brasleira de biologia 2021
Peer-reviewed papers that mention this species alongside captivity, zoos, veterinary care or aquaculture. Some cover several species or mention it only in passing, so check the abstract. See all 116 on PubMed → 170
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.
- Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
- PubMed (U.S. National Library of Medicine) Peer-reviewed researchIndex of peer-reviewed veterinary, zoo and husbandry research.
- 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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