The four most dangerous species of aquarium fish

Let’s face it – some of us like to live a little bit on the wild side and when it comes to our aquariums – it’s not any different. The shallow end isn’t for everyone, after all!

Today, we’ve picked out four ferocious fish that people have had in their tanks. All of them have qualities that make them dangerous – whether it’s to humans or other aquatic life. So if you’re a thrill seeker who likes to live dangerously – these fish are for you.

Now – before we get going with anything – please be advised – each of these fish are extremely dangerous and should only be in tanks of people who are either professionals or extremely experienced. In fact, we recommend that you avoid them altogether. But hey – a little window-shopping never hurt anyone, right?

Let’s jump right in, or well… just look.


Lionfish come ready to rumble with spines they use to take down prey and predators; and even sometimes humans as well. Lionfish are not ‘one size fits all’ however – as there’s a variety of different kinds of Lionfish – the most popular of which is the Red Lionfish. They’re venomous, but not usually fatal for humans. They can grow up to 12 inches in some cases and use spines to take down prey.

Puffer fish

 Puffer fish kind of have this reputation for being cute, but don’t let those adorable, round exteriors fool you; these fish are poisonous and deadly. They use air to expand their bodies when they’re alarmed, and their skin has spines that have tetrodotoxin in them– which is extremely dangerous venom for humans.

Of the fish on this list – this is one you might want to pass on. For one – there’s no antidote for their venom so if you make a mistake – it could cost you dearly. Second, although they’re not predators, if other fish try to mess with them, they’ll likely end up dead. Use the utmost extreme caution.


There’s a lot of fluff surrounding piranhas. No, they don’t attack like they do in the movies, yes they can bite you but on the whole – you don’t have too much to worry about. They almost never attack larger predators or your hands if given the chance. They’re more like vultures, really – as they usually like to scavenge for dead carcasses in the wild.

That being said – you still should – as you would with any dangerous fish – practice extreme caution. They don’t want to attack you, but if they feel threatened they most certainly may and they have extreme force behind their bite – enough to take a finger off if they’re full size. Don’t make sudden movements and don’t mess around.


Without the shadow of a doubt – the stonefish is the most poisonous fish known to mankind. It’s a saltwater fish that has 13 spines on its back that camouflages itself into the sand. Most humans encounter them by accidentally stepping on them and if/when they do – they need IMMEDIATE medical attention.

They grow up to about 16 inches and believe it or not – some folks like having them in their tanks. They’re not exactly the most beautiful fish in the sea, but people certainly get a thrill from owning one of the most dangerous fish out there.

While people do purchase these fish we again want to emphasize – these aren’t for everyone and you need to be extremely cautious. In fact, we just recommend that you pass altogether. These fish are cool to talk about, but they can pose serious risks for you, your family and also your aquarium community.



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