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.。

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。