From garden ponds filled with Koi Carp to the humble goldfish bowl (although goldfish are far happier living in a larger tank) – the UK is a nation of fish lovers.
There are an remarkable five million indoor fish tanks in the UK alone, according to the Pet Food Manufacturers’ Association (PFMA).
That’s about 10 per cent of British households – making fish the third most popular pet after dogs and cats.
It’s a fascinating hobby, particularly for youngsters, and there are few more relaxing activities than watching fish slowly swim around their home.
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There’s plenty of choice when it comes to adding fish to (well prepared and correctly set up) home aquariums, with pet shops offering a bewildering range of colourful and interesting finned friends that will happily live in the corner of your living room.
One of the most important things to note when choosing a new pet fish is whether they are likely to be aggressive - bullying, nipping or even eating their tankmates.
Many fish can co-exist happily with numerous other breeds in so-called community tanks, while others should be kept alone, with other fish of the same breed, or with breeds that are similarly aggressive.
Here are the 18 least, and most, aggressive breeds of popular tropical freshwater fish.
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13. Corydoras Catfish
Perfect to give you a helping hand with cleaning your aquarium, the Corydoras Catfish are bottom-dwelling fish that hoover up any leftover food. They prefer to be kept in groups of at least six and are extremely peaceful. Orinally from South America, they can defend themselves in a fight, thanks to their body armor topped by sharp spines. | Canva/Getty Images
14. Guppy
Another hugely popular staple of community tanks the world over is the brightly-coloured guppy which happily co-exists with other similarly-placid species of fish. The only exception is if they give birth to babies - it's best to pop the baby fish into a different aquarium in case they become a snack. | Canva/Getty Images
15. Swordtail
Swordtails are easy-going fish with an elongated tail resembling a sword - but it's never used for violence. Another fish that likes plenty of vegetation, the males are only occasionally territorial and otherwise this is a very friendly fish. | Canva/Getty Images
16. Celestial Pearl Danio
Also known as the Galaxy Rasbora, whatever you call them the tiny Celestial Pearl Danio isn't going to hassle anybody else in its tank. They look like tiny trout and originally hail from Myanmar and Northern Thailand. | Canva/Getty Images