You've most likely seen piranhas in films as packs of deadly, carnivorous fish that can shave the meat off a chicken bone with their teeth. Those beady eyes and pointy little mouths make these fish look like extraterrestrial terrors. It's really no wonder why they were the star of a Jaws-esque horror film series and in Animal Crossing: New Horizons, it's not much different - in fact, it might be just as creepy.
Players have discovered that if you catch a Piranha, donate it to the museum and look at it in the tank, the little beast stalks you from the water and bashes at the glass in an attempt to attack. You can even hear the bone-chilling sound of the fish's repeated force against the surface, he's furious at you for putting him in a tank and wants revenge at all costs. Fortunately, they can't really escape, or can they? If ants can pull a Houdini, why can't ferocious fish?
Assuming you're feeling brave, you can test this phenomenon out for yourself in New Horizons by catching a Piranha right now while it's available in the Summer season. They can be found in rivers all day long, but with a four-star rarity rating, you'll need to be patient when looking for one. Keep in mind that it'll be gone for the year once September begins, so make sure to do it before then.
Some players disagree with this inclusion, claiming that Piranhas are not nearly as aggressive as Hollywood has portrayed them to be and that some species are even strictly vegetarian. Jeremy Wade, the host of River Monsters, did a test with getting into a pool holding a school of red-bellied piranhas and they did not react to him whatsoever.
Surely the developers did this for fun and had no intention of being scientifically inaccurate, and its the little silly add-ins like this that make Animal Crossing as fun as it is. Now go and catch your own Piranha, but don't get bitten!
Source: Reddit