Whether its lovingly-kept garden ponds filled with Koi Carp to the humble goldfish bowl (although goldfish really need a proper tank to be happy and healthy) – Britain is a nation of fish lovers.
The Pet Food Manufacturers’ Association believe there are an amazing five million indoor fish tanks in Britain - that makes them the most popular animal in the country other than the ubiquitous to cats and dogs.
There’s plenty of choice when it comes to adding fish to (carefully set up) home aquariums, with pet shops offering a bewildering range of colourful and interesting finned friends.
Different breeds of fish have very different attributes - some easy to look after some difficult, some top feeders some bottom feeders, some lively and others happy to slink at the bottom of the tank.
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One of the most important things to note when choosing a new pet fish is whether they are likely to be aggressive - bullying, nipping or even eating their tankmates.
Many fish can co-exist happily with numerous other breeds in so-called community tanks, while others should be kept alone, with other fish of the same breed, or with breeds that are similarly aggressive.
Here are the 26 least, and most, aggressive breeds of popular tropical fish.
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21. 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
22. 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
23. 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
24. 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