From garden ponds filled with Koi Carp to the humble goldfish bowl (although goldfish are far happier living in a larger tank) – the UK is a nation of fish lovers.
There are an remarkable five million indoor fish tanks in the UK alone, according to the Pet Food Manufacturers’ Association (PFMA).
That’s about 10 per cent of British households – making fish the third most popular pet after dogs and cats.
It’s a fascinating hobby, particularly for youngsters, and there are few more relaxing activities than watching fish slowly swim around their home.
Read more: Dog Intelligence 2026: Here are the 22 dogs with the highest and lowest IQs - from the dumb Beagle to the smart Labrador
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 finned friends that will happily live in the corner of your living room.
The first decision to make is whether you are going to pick a freshwater or saltwater tank - saltwater is a little more demanding - before choosing your fish breeds.
It’s important to ensure that you get the right fish for your particular aquarium or your pets will not be happy and healthy.
If space (and money) is no object then there are some incredible huge tropical fish you can opt to put in your enormous tank.
Here are 12 of the biggest - and most colourful - tropical fish for freshwater aquariums.
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5. 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
6. Bala Shark
Peaceful and striking, Bala Sharks can grow up to 14 inches. They’re active swimmers and prefer to be in groups - so are another ideal fish for school fans. The require large, long tanks with plenty of open space and clean water. Not real sharks... | Canva/Getty Images
7. Clown Knifefish
Looking every inch like something from a horror movie, the elegant Clown Knifefish reaches up to a terrifying three feet. Mainly nocturnal (of course they are) they need plenty of hiding places in their huge aquarium home. Highly predatory, they can only share a tank with fish too big to fit in their gaping mouth - and even then it's a bit of a gamble. | Canva/Getty Images
8. Giant Gourami
Reaching up to 28 inches, Giant Gouramis are gentle giants. They’re intelligent, long-lived, and can become attached to their keepers. With a face only a mother could love, they need large tanks and plenty of open swimming space. A naturally friendly creature, they can coexist with similarly-sized fish. | Canva/Getty Images