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.
1. Piranha
We're starting with the fish that have temperaments that make them unlikely to get on with other species of tankmates. 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. 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
3. 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
4. Red Devil Cichlid
Not content with being aggressive to other fish, the Red Devil Cichlid is also known for attacking everything from tank decorations to plants. They are tremendously charismatic fish though and a joy to own - just don't expect them to have any finned friends. | Canva/Getty Images