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No federal permit to keepGoldfish
Carassius auratus
Fishes › Carp, barbs, minnows, loaches (Cypriniformes) › Cyprinidae (Carps and barbs)
The goldfish (Carassius auratus) is a freshwater fish in the family Cyprinidae of the order Cypriniformes.
Care at a glance
Species-specific values
Values researched for this exact species. Where they differ from the group guide below, follow these. Air, surface and water temperatures are listed separately, and each source is kept as published rather than averaged.
| Minimum tank volume | 50 L RSPCA minimum must ALSO meet adult-body-length dimensions and grow with fish number; slim active varieties need more space. | 267 |
| Minimum tank dimensions body length | length: 4 adult body lengths; width: 2 adult body lengths; height: 3 adult body lengths Dimensions must be based on eventual adult size; volume alone is insufficient. | 267 |
| Water temperature | 68–75 °F (20–24 °C) RSPCA ideal aquarium range; do not confuse with the full outdoor seasonal tolerance range. | 267 |
| Water pH | 6.5–7.5 | 267 |
| Typical lifespan | 10–15 years | 267 |
| Reported lifespan upper | 30 years Some varieties with appropriate care; not an average or guarantee. | 267 |
| Social | Social; increase space and filtration with fish number. | 267 |
Species-specific aquarium care
- Tank: At least 24 in long and 12 in front to back for one adult (adults commonly reach about 3.9 in / 10 cm; the largest recorded was 18.9 in).
- Water: Freshwater (tolerates brackish).
- pH: 6–8.
- Hardness: 5–19 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.
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
Goldfish and koi
Applies to most species in this group. Habitat: Ponds and slow rivers. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- For goldfish, RSPCA Australia specifies at least 50 L and dimensions at least four adult body lengths long, two wide and three high; larger, active fish need more space. Apply a separate adult pond plan for koi.
- Heavy filtration; they produce a lot of waste.
Diet
- Sinking pellets and vegetables for fancy goldfish; koi pellets for pond fish.
Social life
- Social; keep in groups.
Health watch
- Swim bladder problems in fancy goldfish; KHV (koi herpesvirus) in koi. Never release goldfish or koi into natural waters.
Understanding the animal
About this animal
About this animal
It is commonly kept as a pet in indoor aquariums, and is one of the most popular aquarium fish. Goldfish released into the wild have become an invasive pest in parts of North America and Australia.
Quoted from the Wikipedia article “Goldfish” (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 and brackish water, in rivers and streams, lakes, rice paddies. Uses both the bottom and open water. Inhabit rivers, lakes, ponds and ditches. |
| Ground it lives on | Over mud, vegetation. |
| Water it lives in | Freshwater / brackish water, pH 6–8, hardness 5–19 dH, depth 0–20 m. |
| Climate | Subtropical climate. |
| Wild diet | Grazing on aquatic plants. |
| Behavior to plan for | Breeding: open water/substratum egg scatterers. |
What this means for care
- Use a soft, fine bottom; it lives over fine sediment in the wild.
- Add plants, roots, wood or leaf litter like its wild habitat.
- It tolerates or needs brackish water; check salinity needs before setup.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 81°F (up to 92°F in the hottest sampled areas) |
| Cool-season lows | about 31°F (down to 14°F in the coldest sampled areas) |
| Average temperature | 45–65°F across sampled records |
| Relative humidity | 66–77% on average (driest month about 64%) |
| Rainfall | about 809 mm a year, spread fairly evenly |
| Winters | Cool to cold winters (lows around 31°F) in much of its native range. Seasonal slowdown may be relevant, but species-specific biology determines whether brumation or hibernation occurs. |
Measured at 3737 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 goldfish (Carassius auratus) is a freshwater fish in the family Cyprinidae of the order Cypriniformes. It is commonly kept as a pet in indoor aquariums, and is one of the most popular aquarium fish. Goldfish released into the wild have become an invasive pest in parts of North America and Australia. Native to China, the goldfish is a relatively small member of the genus Carassius (which also includes the Prussian carp and the crucian carp). — 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 |
| Behavior | Goldfish are a social species. — Animal Diversity Web |
| Reproduction | Cold water temperatures during the winter months are necessary for proper ova development. Spawning takes place in shallow water among weeds, often where willow roots grow exposed in water, also meadows inundated by spring flood. Spawning activity begin just before dawn, to midafternoon. — FishBase |
| Lifespan | Goldfish usually live from 20 to 30 years in the wild and 5 to 10 years in captivity. — Animal Diversity Web |
| Appearance and size | Goldfish hatch with dark, pigmented scales, but they depigment 2-3 months after hatching. — Animal Diversity Web |
| Biology | Adults inhabit rivers, lakes, ponds and ditches (, 10294 ) with stagnant or slow-flowing water. They occur in eutrophic waters, well vegetated ponds and canals. Live better in cold water. — FishBase |
| History and naming | There has been considerable debate about the taxonomy of the goldfish. Previously, the goldfish was believed to be either a subspecies of the crucian carp (Carassius carassius), or of the Prussian carp (Carassius gibelio). However, modern genetic sequencing has suggested otherwise, and that modern goldfish are domesticated varieties of C. auratus that are native to Southern China. — 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.
Fancy Goldfish (domesticated forms)
- OATA describes 15–23°C water as optimal within a broader tolerance range. Single-source published guidance.1
- OATA recommends 100 L for an adult, with 50 L additional water per further adult, filtration, and gentle flow. Treat this as a starting stocking recommendation, not a complete bioload formula.1
- Fancy and faster common-type fish can differ in food access. Assess compatibility rather than grouping solely by species name.2
- OATA targets no measurable ammonia or nitrite. Its nitrate advice is relative to source-water nitrate, not an automatically interchangeable absolute concentration. Preserve chemical form and units.1
The numbers
The numbers
Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.
Maximum recorded lifespan
Longest recorded lifespan reported by each database; typical lifespans are usually shorter.
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.
pH
Water hardness
Veterinary & husbandry research
Veterinary & husbandry research
- Detection of mycobacteria in aquarium fish in Slovenia by culture and molecular methods Pate M et al., Diseases of aquatic organisms 2005
- Development of Vaccines Against Nocardiosis in Fishes Nayak SK et al., Methods in molecular biology (Clifton, N.J.) 2016
- Microbial diversity and potential pathogens in ornamental fish aquarium water Smith KF et al., PloS one 2012
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 320 on PubMed → 170
Sources for this sheet
- AnAge: The Animal Ageing and Longevity Database (Human Ageing Genomic Resources) Peer-reviewed researchCurated, referenced longevity and life-history records for thousands of species; maximum lifespans are often from zoo animals.
- 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.
- 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.
- RSPCA Australia — How should I care for my goldfish? Expert educator & keeperAdded 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.
- 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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