LONDON -- There's a reason you never catch Dementors in water, and it's not because they don't like getting their cloaks wet.。

The real reason is obvious: there are far too many magical fish out there that would blast them into oblivion with their tiny, adorable patronuses.。

SEE ALSO:'Harry Potter' fans, rejoice: You can now discover your true Patronus
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Just look at this one in action:。

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OK, so it's probably worth mentioning at this point that fish can't really cast Patronuses (at least not that us muggles know about, anyway). 。 The little cardinal fish in the 。BBC Earth 。

clip above -- which went viral after it was shared recently on Twitter -- is actually regurgitating a creature called an ostracod, which gives off that bright blue light when swallowed as a form of defence.。 Then again, who knows?Then again, who knows? Maybe that's what they just 。

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