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.
13. 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