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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9. Bucktooth Tetra
Most Tetras - like the much-loved Neon Tetra - are chilled and happy-go-lucky fish. The exception is the Bucktooth Tetra, which has the nasty habit of nibbling scales off other fish, leaving them open to potentially-fatal infections. If you want to keep these you'll probably not want any other species of fish in the tank. | Canva/Getty Images
10. Neon Tetra
Moving onto the non-aggressive fish happy to share a tank with myriad finned friends. Neon Tetras are one of the world's most popular tropical fish, with the small, schooling fish known for their striking blue and red stripes. It's best to keep at least six so they have a group of buddies to swim around with. This is a fish that doesn't have an aggressive scale on its beautiful body. | Canva/Getty Images
11. Harlequin Rasbora
Harlequin rasboras are known for their distinctive orange bodies with black triangular markings and have been kept in aquariums for over a century. They are another schooling fish that are happiest in groups of six or more and are the perfect hardy fish for beginners. Their peaceful nature allows them to coexist with a wide range of community fish. | Canva/Getty Images
12. Platy
The Platy is a colourful and easy to care for fish that mixes well with others thanks to their complete lack of aggression. There are actually two species - the Southern Platyfish and the Variatus Platy - but they are hard to tell apart and most fish bought from pet shops will have been interbred from the two. They can live for up to three years and come in a variety of colours, including red, yellow, orange, blue, rainbow and white. | Canva/Getty Images