Goldfish
Scientific name: Carassius auratus
Traditional ornamental fish, perfect for ponds and large aquariums.
Quick facts
- Approximate size15–30 cm (in ponds)
- Average weight200–500 g
- Life expectancy10–20 years (well maintained)
- ActivityDiurnal
Basic information
- Habitat: slow-flowing freshwaters, ponds, and shallow lakes.
- Diet: omnivorous; consumes algae, small invertebrates, detritus, and prepared food.
- Sexual dimorphism: during breeding season, males may show breeding tubercles on opercula and fins.
- Predators: larger predatory fish, aquatic birds, and some carnivorous mammals.
Life in the wild
How this species lives in its natural environment, with the waters, shelters and resources it needs.
Origin and habitat
It descends from Asian carp that inhabited rivers and lakes of temperate waters. In semi-wild state it is found in ponds, canals, and water bodies with gentle current.
Natural behavior
It is a gregarious fish that forms groups to feed and move. It spends much of its time searching for food on the bottom and among vegetation.
Ecological impact
When released into the wild outside its original range it can become invasive, altering ecosystems and displacing native species. It should never be released into rivers or lakes.
Curiosities
Some interesting facts about the goldfish that help understand its real needs.
- It can live more than 10 years, and even exceed 20 in well-maintained ponds.
- Long-tailed or round-bodied varieties are more delicate than elongated forms.
- Its fame soared in Asia as an ornamental animal hundreds of years ago.
- Typical small unfiltered fishbowls do not meet minimum welfare conditions.
Welfare profile
Key points to offer good conditions to a goldfish in an aquarium or pond.
Space requirementHigh
They are large and very active fish. They require large aquariums or, ideally, spacious ponds with plenty of water available.
Water qualityHigh
They produce a lot of waste, so they require powerful filtration and frequent water changes to avoid accumulation of toxins.
CompatibilityMedium
They can coexist with other goldfish and species of similar size and calm temperament, always in facilities sized for the group.
Goldfish in captivity
General tips for responsible maintenance, away from the image of "fishbowl fish".
⚠️ Goldfish sold at fairs or as prizes often end up in very poor conditions. It is preferable not to support such practices.
Is it suitable as a first fish?
It can be a good option if you have a large aquarium or pond and understand its real adult size. It is not if you intend to keep it in tiny containers.
Basic requirements
Spacious aquariums or ponds with good filtration. Warm, oxygenated water with stable parameters. Varied diet with quality specific food. Avoid overpopulation, which generates stress and health problems.
Common mistakes
Keeping them in small fishbowls, not using a filter, overfeeding them, or mixing many different species in little water volume.
Long-term commitment
Well cared for, they can accompany the family for many years. Before adopting them, it is advisable to plan the space they will need as adults.