Goldfish

Overview

Goldfish (Carassius auratus) are freshwater fish belonging to the family Cyprinidae. Native to China, they are one of the most popular pet fish in the world and are commonly kept in indoor aquariums.

Selective breeding began in imperial China more than 1,000 years ago, and today there are around 300 recognised breeds. They vary greatly in size, body shape, fin configuration, and colour - with combinations of white, yellow, orange, red, brown, and black all known.

Goldfish were introduced to Europe in the early 1600s, arriving in Portugal in 1611 and reaching North America around 1850. They have a long and fascinating history as ornamental fish kept by emperors and everyday families alike.

Temperament & behaviour

Goldfish are gregarious by nature and naturally display schooling behaviour. They are generally peaceful towards one another - it is very rare for one goldfish to harm another.

They are surprisingly clever. Goldfish have a memory span of at least three months and can distinguish between different shapes, colours, and sounds. They can even tell individual humans apart, often swimming eagerly to the front of the tank for their regular owner while staying cautious around strangers.

Over time, goldfish learn to associate their owners with food and may appear to "beg" at feeding time. With patience, some can even be trained to respond to light signals or perform simple tricks using positive reinforcement.

One thing to be aware of is feeding competition. Faster varieties like commons and comets can easily eat all the food before slower, fancier varieties get a look in. It is a good idea to keep breeds of similar body type and swimming ability together.

Care basics

Goldfish are freshwater fish and need a well-maintained aquarium with good filtration. They produce a large amount of waste through their feces and gills, releasing harmful chemicals into the water, so waste can build up to dangerous levels surprisingly quickly.

Space matters. Common and comet varieties need around 20 US gallons (roughly 76 litres) of water each, while smaller fantail goldfish need around 10 US gallons (roughly 38 litres) each. Although it is a myth that goldfish simply grow to fit their tank, their growth rate is influenced by the size of the tank.

Breeding typically happens after a significant temperature change, often in spring. Eggs are adhesive and attach to aquatic plants, hatching within 48 to 72 hours. Bear in mind that adult goldfish may eat young fry if they encounter them.

Health awareness

Goldfish produce a lot of waste, and a build-up of harmful chemicals in the water can become life-threatening relatively quickly. Keeping a close eye on water quality is one of the most important things you can do for your fish's wellbeing.

Some highly selectively bred varieties are less hardy than breeds closer to the original wild type. Fancy breeds with unusual body shapes or eye configurations may need extra attention and are generally better suited to aquarium life than outdoor ponds.

Goldfish are able to survive short periods without oxygen, which researchers believe is an adaptation to cold conditions - but this should never be relied upon. Always ensure your tank is properly aerated and maintained.

If you notice changes in your goldfish's behaviour, appetite, or appearance, it is always worth seeking advice from a vet with experience in fish.

This is general awareness only, not veterinary advice. Always consult a vet about your pet's health.

Fun facts

Goldfish can see ultraviolet light - they have four types of cone cells in their eyes, making them tetrachromats. That means they can actually see more colours than we can!

The largest goldfish on record was believed to measure 19 inches (48 cm), found in the Netherlands in 2008. Closer to home, a goldfish named Goldie kept in Folkestone, England, measured 15 inches and weighed over 2 pounds at the same time.

In 1620s southern Europe, goldfish were considered so special that married men would give their wives a goldfish on their first wedding anniversary as a symbol of good fortune - though the tradition faded as goldfish became more widely available.

Yellow goldfish were once reserved exclusively for the Chinese imperial family - ordinary people were forbidden from keeping them, as yellow was the imperial colour.

Source

Adapted from Wikipedia (CC BY-SA 4.0): https://en.wikipedia.org/wiki/Goldfish