Housing Some goldfish can be kept in garden ponds throughout the year, whereas all goldfish can be housed in a coldwater aquarium indoors, with no heating required. Choose a rectangular rather than a circular tank to give the fish more space. They can easily grow to 15-20cm or more, and are rather clumsy when swimming, so only include floating plants in an aquarium with large goldfish – others will be uprooted.

Care Don’t overfeed! This will otherwise be fatal, with leftover food piling up in the aquarium. Offer several snacking opportunities through the day, rather than one massive meal, providing no more food than will be eaten in about 5 minutes. An undergravel and/or power filter helps to maintain water quality, but change about a third of the aquarium water every two to four weeks. Always add a water conditioner before adding fresh water to the tank. Otherwise, chlorine compounds in tap water can kill your fish. Ensure the temperature of the water are the same.

Temperament Pretty placid as a general rule, agreeing well together. Said to have a very limited memory, but never forget to come for food! Males, recognisable by the white spots that develop on the gill covers behind the head, will chase females who swell with eggs when in breeding condition.

Varieties Hardy varieties which can live outside through the year have long, stream-lined bodies, and include the mottled Shubunkins, as well as the common goldfish itself, which can actually be white or even canary yellow. The jewel of the indoor varieties is the Pearlscale, whose scales look like mini-pearls, glistening along the sides of the body. The Moor is a lustrous, matt black variety and also popular is the striking Red-capped Oranda, with its silvery-white body and red area on the head. There are also plenty of different fin types too, including the elegant Veiltail, not to mention the rather dumpy Lionhead.

Did you know? Goldfish are descended from dull greenish carp being farmed for food in China over 1700 years ago. Some of these fish started to show orange markings. They were selectively bred, caught the eye of successive emperors and ending up as an integral part of Chinese culture. Taken to Japan during the 1500s, they finally reached Europe about 200 years later, but remained largely unknown in the USA right up until the 1890s.

Lifespan Goldfish have been known to live for over 40 years, they will only live long if they have the space to grow. Likely illnesses Short-bodied goldfish may gulp down air when feeding at the surface and this adversely affects their buoyancy, causing them to swim at strange angles. Give these varieties sinking food will help to avoid the problem. Goldfish can also sometimes develop wart-like growths on their bodies, but these are not usually serious. Do watch for fungus on their fins or bodies though, which creates a haloed appearance and is often caused by poor water quality. Can be cured if caught early.

Equipment needed Aquarium with a hood and light, water conditioner, suitable filter(s), floating plants and gravel for those indoors, or suitable pond and plants for outdoor goldfish. Prepared goldfish food – flakes or pellets. Will also require a water test kit to ensure water quality, plus a net.