From garden ponds filled with Koi Carp to the humble goldfish bowl (although goldfish really need more space to be happy and healthy) – the UK is a nation of fish lovers.
According to the Pet Food Manufacturers’ Association there are an incredible five million indoor fish tanks in Britain - that makes 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.
But you should be aware that while some fish are placid and happy to live in a ‘community tank’ with a mixture of other species, others are predators that can cause serious issues for other fish.
They can still make great - and fascinating pets - but just need their own space away from potential prey.
Here are 13 of the most aggressive to watch out for.
9. 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
10. 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
11. 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
12. Red Tailed Black Shark
A popular aquarium fish, the Red Tailed Black Shark is particularly known for showing aggression to other Red Tailed Black Sharks, so you're best to only have one in an aquarium. They can be kept with other species, but may cause problems with particularly docile tank-mates. | Canva/Getty Images