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.
The first decision to make is whether you are going to pick a freshwater or saltwater tank - saltwater is a little more demanding - before choosing your fish breeds.
One of the most important things to note when choosing a new pet fish for a freshwater tank 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 12 of the most aggressive breeds of colourful tropical fish - caution is recommended.
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1. Pirahana
In news that will surprise nobody, the notorious Piranha isn't the sort of fish that mixes well with others. There are a number of different species which grow to different sizes, but all of them have razor-sharp teeth meaning you should also be careful where you put your fingers. | Canva/Getty Images
2. Tiger Barb
Individually small and relatively harmless, Tiger Barbs become highly aggressive in groups. They relentlessly nip fins of slower fish, causing injuries and stress. Their pack aggression makes them notorious bullies and feared by other fish. | Canva/Getty Image
3. Flowerhorn Cichlid
Originally from Southeast Asia, the Flowerhorn Cichlid is a stunning fish but its aggressive and territorial nature means they aren't suitable for community tanks. These are fish best kept on their own or with perhaps one other similarly-sized fish of the same species. Luckily they are so beautiful you might not want any other fish. | Canva/Getty Images
4. 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