Scared Of Sea Beasties? These 4 Freshwater Monsters Might Just Put You Off Rivers Too

The ocean is packed with scary-looking stuff. I mean, have you seen the things that live in the Mariana Trench? Terrifying. But if you thought all the horror movie inspiration was confined to the seas alone, then hoo boy, just wait until you see what’s lurking within the world’s fresh waters.

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Giant freshwater stingray

You know something is big when “giant” doesn’t really feel like a good enough word to describe it. Given that the giant freshwater stingray (Urogymnus polylepis) can be over 2 meters (6.6 feet) wide, 4 meters (13.1 feet) long, and weigh up to 300 kilograms (661 pounds) – that’s more than a grizzly bear – maybe we should start calling it the “f***ing massive freshwater stingray”. If scientists are allowed to call a tiny frog Mini ature, our suggestion really shouldn’t be a problem.

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Found in river systems across patches of Southeast Asia, these stingrays are known to be quite chilled out, and don’t readily attack humans. Still, you wouldn’t want to get on the wrong side of one. Unsurprisingly, given their general giant-ness, these stingrays also have a big ol’ barb that can be over 35 centimeters (13 inches) long. Not only could that leave you with a pretty significant wound, but also some rather unpleasant toxins. Double ouch.

Diving bell spider

Our sincerest apologies to anyone who thought they could escape from spiders by heading into water – the diving bell spider (Argyroneta aquatica) has absolutely no problem with a bit of moisture. In fact, it’s the only spider that lives almost entirely underwater. That’s all thanks to its “diving bell”, a submerged structure made out of its silk that’s filled with air the spider brings down from the surface.

The good-ish news for any water-loving arachnophobes out there is that diving bell spiders are at least quite small, measuring between 8 to 15 millimeters (0.3 to 0.6 inches) in length, so could be easily missed underwater.

Goliath tigerfish

The Goliath tigerfish (Hydrocynus goliath) is called that for a good reason. It’s no FMFS (see above), but it’s still a hefty fish, with the biggest one ever caught clocking in at 70 kilograms (154 pounds) and measuring 1.5 meters (4.9 feet) in length.

But it’s not the size of this fish that’s intimidating – no, it’s those teeth. Combined with a super strong jaw, these dagger-like gnashers can rip clean through prey in a single bite. It’s only on rare occasions that they’ve used that bite on humans, and even then, it’s unlikely that humans were specifically targeted – but you’ll forgive us if we don’t really fancy running into the water with them.

Candiru

If you’ve heard anything about candiru, it’s likely to be something about how these little catfish can allegedly lodge themselves in people’s urethras and other bodily holes you’d rather not have a fish living in. Thankfully, that doesn’t seem to be true, but that’s not to say you’ll come out of an encounter with a candiru unscathed.

Some of them have a taste for blood, and back in 2021, one unidentified species of candiru was found to have latched onto a young boy’s back in order to get it. It apparently took some force to get the fish off, leaving its victim with a nasty elliptical wound.

It’s not clear exactly how common attacks by bloodthirsty candirus on humans are, but other candiru species that are carrion-eating have been known to eat human corpses. They’re just doing what they need to do to survive, of course – but that doesn’t mean we have to be happy about it.