Common Goldfish

Looks how to spot one

Scaled, single-tailed streamlined body

The classic goldfish shape: a sleek, torpedo-like body with shiny scales, a single dorsal fin and a short, fairly stubby forked tail. That short tail is the easiest way to tell it from the comet, whose tail can be more than half its body length. Common goldfish are fast, strong swimmers and, given room, can grow well past 30 cm; FishBase lists 48 cm as the largest recorded for the species. Wild-type fish are olive or brown, and colour in domestic fish can shift with light, diet and age.1236

Personality what they are like

Peaceful, curious and surprisingly smart. Common goldfish quickly learn who feeds them and when, will gather at the front of the tank at mealtimes and can become tame enough to take food from a hand. They are lively swimmers that tend to enjoy the company of other goldfish.125

Daily activity how busy a day looks

High. This is one of the faster, more energetic goldfish types and it needs long, open swimming room, which is why large tanks or garden ponds suit it best. It mostly swims in the middle of the water column.672

Grooming and care the hands-on bits

Coldwater fish: RSPCA advises 10 to 21 C, while Wikipedia puts the comfortable range at about 20 to 22 C; a heater is usually unnecessary. pH about 6.0 to 8.0. Goldfish produce a lot of waste, so strong mechanical and biological filtration, weekly water changes of about 30%, fortnightly checks for ammonia and nitrite (both should be zero) and dechlorinated tap water are key. Cycle a new tank for at least two weeks before adding fish.8423

Home where they are happiest

Much more space than most people expect: RSPCA advises at least 60 litres of water per goldfish, and Wikipedia suggests about 20 US gallons (roughly 75 litres) per adult common or comet goldfish; FishBase gives a minimum tank length of 100 cm. Wide tanks beat tall ones for oxygen, an air stone helps, and the tank should sit away from direct sun and radiators. Round bowls are unsuitable. A well-filtered garden pond is an excellent home for adults. In the wild the species lives in slow or still, well-planted rivers, lakes, ponds and ditches.823

Food basics what goes in the bowl

Omnivore. Use a goldfish-specific pellet or flake (not tropical food) and add vegetables such as chopped peas and spinach. Daphnia, brine shrimp and bloodworm make good occasional extras. Feed small amounts that are eaten within about 2 to 5 minutes, once to three times a day; slight underfeeding is better than overfeeding. Wild goldfish eat plankton, small invertebrates, plants and detritus.513

Company who they like around

Sources differ: Wikipedia describes goldfish as sociable fish that prefer groups and FishBase suggests groups of 5 or more, while the RSPCA says a goldfish can live happily on its own. If kept together, house common goldfish only with other fast single-tailed types (such as comets or shubunkins), not slow fancy twin-tailed goldfish, which can lose out at feeding time.136

The story where it all began

Red, orange and yellow colour variants of wild carp were first noted in China during the Jin dynasty (266 to 420). By the Tang dynasty (618 to 907) gold-coloured fish were being kept in ornamental ponds, and by the Song dynasty (960 to 1279) selective breeding of goldfish was well established. The fish reached Japan in 1603 and Portugal in 1611, spreading across Europe from there, and arrived in North America around 1850. In the United States, Henry Bishop of Baltimore became known as the 'Gold Fish King' and sold over a million fish a year. The common goldfish, the plain single-tailed original, remains the base stock from which the many fancy varieties were bred, and it is still one of the world's most familiar pets.21

Recognised by the official bits

IUCN Red List

Carassius auratus assessed as Least Concern (4 August 2010)3

RSPCA

Singles out common goldfish as the hardiest goldfish type because they have not been reshaped by selective breeding4

Taxonomy

Family Cyprinidae (carps and minnows)2