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.
5. Pea Puffer
The Pea, or Dwarf, Puffer is one of numerous species of Puffer Fish - and one particularly popular with aquarium owners. Some are tremendously toxic and all tend to display aggression to tank-buddies. Keep them away from other fish though and they make fascinating pets. | Canva/Getty Images
6. Jack Dempsey Fish
Originally from Central American countries like Mexico and Honduras, the Jack Dempsey Fish is named after a famous 1920s boxer thanks to its fearsome face and aggressive nature. Best kept alone in a tank, it's also important to provide them with somewhere to hide away. | Canva/Getty Images
7. Peacock Bass
The Peacock Bass is a fish for serious aquariasts only - needing at least a 150 gallon tank. A predatory species, if they get peckish they'll eat pretty much anything put in front of them, including other Peacock Bass. | Canva/Getty Images
8. Oscar Fish
Another species of aggressive cichlid, the Oscar Fish is a natural born bully that will happily eat small fish by the shoalful. If you are going to keep other fish with them they need to be of a similar size and of an equally aggressive nature. | Canva/Getty Images