Carp diem: how to look after your lockdown goldfish for life

This is the year many people realised that what was missing from their lives was a pet. Companion animals brighten our days – and give us someone else to talk to once we’re bored with the people with whom we’re “staying at home”. But dogs are a hassle, and cats are murderous. So, lots of people think a fish or two might be the answer.

According to the retailer Pets at Home, there has been a resurgence of interest in fish-keeping . However, while goldfish are considered a low-maintenance pet, you should not be fooled, says Suzanne Constance. A goldfish expert, Constance runs the It’s Not Just a Fish campaign, which advocates for better care for aquarium fish. “People think ‘my mate had one from the fair in the 1970s and they live in bowls’,” she says. “It’s that kind of fake knowledge that makes people think it will be easy.”

Big fish

It’s a myth that fish only grow to the size of its tank, says Constance. “Goldfish want to be a 12in carp, that’s what they’re designed to be,” she says. Lots of them won’t get that big, “but they are going to grow”. The “starter tanks” you can get in pet shops are for baby fish. It’s a bit controversial, she admits, and “there are a lot of people who will disagree with me on this”, but she believes a goldfish needs a tank about 120cm long. It means more swimming space, and more water to dilute their waste. “You’re not constantly battling poor water conditions, or cramped fish, or your fish getting ill.” It also means you can keep more than one. They are sociable fish, says Constance. “We’d like people to keep three or so.”

INTERESTING FACT ABOUT YOUR PET: The United States has the highest pet dog population in the world. Approximately 75.8 million in fact.

Goldfish are sociable so at least three in a tank is best.Goldfish are sociable so at least three in a tank is best. Photograph: novifoto/Getty Images/iStockphoto

Fishy behaviour

Don’t assume fish make dull pets. A happy goldfish, says Constance, is a bit like a labrador. “It will bounce around, it’s very enthusiastic, wants to eat lots of food and is very energetic. If your labrador is sitting in the corner all the time, you know something’s wrong with it. It’s similar with fish – you can generally tell when they’re trying to tell you that something’s not right with their environment.” They might be lethargic or not interested in food. “You can learn to read their body language – if they clamp their fins close to their body, then something’s wrong.”

Do goldfish get bored?

As well as being sociable, “they like stuff to do”, says Constance. At this point, you may be feeling guilty about your childhood fish swimming round and round a small, empty bowl. “They like plants, decor, ‘bubble curtains’ and interesting things to do. They are very intelligent, and they have got quite a long-term memory, far more so than popular myth would have you believe.” A University of Plymouth study found that a goldfish’s memory can last for up to three months . Constance says they “learn to recognise their keepers, they learn who’s bringing them food. And they can see in colour.” Better than us in fact – they can perceive ultraviolet light. “They’re a lot brighter than people think they are,” says Constance.

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Fish food

There is a common misconception that you shouldn’t overfeed a goldfish, says Constance. This is mainly an attempt to manage water quality in tanks that are too small; the poor fish end up hungry. She prefers pellet food rather than flakes (the fish can take in air when grabbing flaked food that is sitting on the surface of the water). Ideally, soak the dry pellets for a few minutes beforehand – dried food can swell in a fish’s stomach. Goldfish appreciate a varied diet, rather than years of boring pellets, and this can include aquatic plants as well as vegetables such as blanched broccoli and shelled peas; adults can be fed twice a day (there is a lot more information online).
If you can’t fit a big-enough tank inside, consider keeping fish in a pond.If you can’t fit a big-enough tank inside, consider keeping fish in a pond. Photograph: Charlotte Observer/Tribune News Service/Getty Images

Clean up

Goldfish are not exactly low-maintenance. Cleaning the tank has to be done once a week, for instance. “You should do at least a 25% to 30% water change,” says Constance. With a suitably large tank, “you’ve got to put aside an hour or two a week to clean and maintain it”.

A goldfish is for life

A common goldfish, says Constance, can live for up to 40 years. For a fancy variety, the lifespan is about 10 to 15 years. “The fact that people think they don’t live very long is a reflection on the kind of care they have,” she says. “It gets to five years old and dies and you think: ‘Oh, that’s done well’, but it really hasn’t.” If you don’t have a large tank, a common goldfish would be happier in an outdoor pond, she says (the fancy ones should be kept inside, or in a heated pond). Rehoming a goldfish can be tricky, she says – far better to do your research first to see if you can look after it properly. “I think a lot of people would research a dog or cat with a lot of effort, but everyone thinks fish are easy.” For information, she recommends Practical Fishkeeping magazine, and says there are lots of Facebook groups that can offer advice.

INTERESTING FACT ABOUT YOUR PET: Having a dog in the house means more bacteria enters the home and gets inside the occupants (one study found “dog-related biodiversity” is especially high on pillowcases.) In turn, people with dogs seem to get ill less frequently and less severely than people with no pets.

Go tropical

Most people don’t have the space to care adequately for a goldfish. “There’s a drive within the fishkeeping sector to try and get people to look at smaller fish,” says Constance. Tropical fish are actually easier to keep, she says. You will need a heater, but the tank can be much smaller (and coldwater and temperate fish shouldn’t need a heater). “They’re really pretty and very interactive, and quite straightforward to keep.” A tank could be kept in a child’s bedroom for instance. “You can teach them a bit of water chemistry and a bit of biology and responsibility. It’s much more fun than poor old goldie being stuck in a corner being miserable on its own.”