From garden ponds filled with Koi Carp to the humble goldfish bowl – the UK is a nation of fish lovers.
The Pet Food Manufacturers’ Association (PFMA) say there are an incredible five million indoor fish tanks in Britain.
Around 10 per cent of British households own pet fish – making them the third most popular animal to welcome into our homes after cats and dogs.
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.
One thing you need to be aware of is that some species are naturally more aggressive than others - with some, you might end up waking up in the morning to find you only have one pet left.
Meanwhile, others are totally chilled and happy to mix with others - perfect for so called ‘community tanks’ with a range of species co-existing.
Of course, more aggressive fish can make for fascinating pets too - you just need to be more careful of who you put in their with them
Here are the 18 most - and least - aggressive species of tropical fish.
9. Betta fish
Like humans, the majority of aggression in beautiful Betta Fish is confined to the males - giving them their alternative name of Siamese Fighting Fish. Males can become aggressive even if they are able to see a competing Betta Fish in another tank. | Canva/Getty Images
10. Neon Tetra
We're now moving onto the least aggressive pet fish that will get on with pretty much anybody (or anyfish). The Neon Tetra is the UK's (and probably the world's) most popular tropical fish. The tiny fish's bright red and blue colouring and ease of care are a winning combination for all tank owners. They originally come from backwater streams in the Amazon basin in South America and don't have an aggressive scale on their body. | Canva/Getty Images
11. Guppy
The beautiful Guppy is one of the most low maintenance tropical fish out there - easy to keep and non-aggressive to fellow fish. Also known as the Millionfish or Rainbow fish - which have large multi-coloured tails and originally come from northeast South America. In common with some other common aquarium fish, they live-birth their young, rather than laying eggs. Many first time fish owners have been delighted to wake up one morning to find tiny Guppy babies have arrived overnight. | Canva/Getty Images
12. Corydoras Catfish
It's always good to have a helping hand with cleaning your tank and that's exactly what the Corydoras Catfish offers. It's a bottom feeding species that will happy clean up any food that has dropped to the bottom of the tank. Native to South America and Central America, they get on very well with other species of fish and are rarely aggressive - the only think they'll be attacking is detritus. | Canva/Getty Images