These Fish Eat Scales


[♪ INTRO] You’re probably pretty familiar with the
Hollywood image of piranhas. The water starts churning, and suddenly an unlucky animal is nothing but a bare skeleton. And yeah, piranhas can definitely do some
damage, but most of them aren’t these ferocious
monsters. They eat lots of different things, and many
piranhas — along with other tropical fish — have evolved one pretty creative feeding strategy: they steal scales off of other fish. The act of eating another fish’s scales
is known as lepidophagy. Part of the reason this is a thing at all
is that scales can actually be a pretty good food source— they’re high in protein and important minerals, and they’re easy to come by. If you’re a fish, anyway. No one even has to die in the process! Fish can just do a drive-by and scrape off
some scales to go. That said, most scale-eating species don’t
only eat scales. For the most part, they just go in for a nibble when competition for resources gets stiff. They eat scales to supplement their regular
diet. And they’re not too discriminating. If they need a bite to eat, they’ll steal
scales off just about anyone–even fish from their
same species! As for how they go about it, they have a few
different methods. Some fish use stealth to snag scales, or speed
to grab ’n’ go. Some bite scales off cleanly, while others
scrape or chew them loose. No matter what the fish’s method of choice
is, a special diet calls for special tools. And some fish have adaptations precisely for
eating scales. For example, typical piranhas have wide jaws that give them excellent leverage for deshingling
the side of a passing fish. And certain African cichlids are so ready
for scale-snacking that their mouths even grow at an angle. These fish can be left- or right-mouthed,
and they’ll typically come at a fish from their dominant side and
use their mouths to twist off scales. Meanwhile, the wimple piranha has opted for
a more… straightforward tactic. It approaches a fish from the side, then uses
its blunt face to basically T-bone its victim at full speed
with its mouth open. The collision knocks scales loose, and the
piranha then catches them as they sink. Seems like overkill, but whatever works, I
guess. However they do it, these fish are able to
get the nutrition they need through a uniquely renewable resource. Because the best part is, scales grow back! It’s probably a little unpleasant to get
T-boned by a piranha, but in general, the fish that get their scales
stolen or smashed off just bounce back fine. Turns out, losing scales and regrowing them is a natural part of fish life. So as weird of a tactic as it is, lepidophagy probably evolved as a strategy for when food
sources are low. Scales are plentiful, and this way, small
predatory fish that can’t find enough smaller prey can
always graze on larger fish that are too big to take down. It’s a niche these fish can really thrive
in, and it makes them unique among even their
closest relatives. So while it may be a fish-eat-fish world most
of the time, some tropical predators have found a more
peaceful way to coexist. Thanks for watching this episode of SciShow! And thank you to our patrons for making videos
like this possible. It takes a lot of people to make a SciShow
video, so your support goes a long way. And if you’re not a patron but you like
what we do, you can learn more at patreon.com/scishow. [♪ OUTRO]

  1. Kurtis Smith

    I was literally just thinking "I want some scales!" Salmon beef jerky that is with skin and scales. It's like normal beef jerky but little fishy. =)

  2. Ivy Princess

    I found this channel today and I absolutely love the videos

    I’m honestly surprised that I just so happened to refresh the page on YouTube in time to be only 25 minutes late lol

  3. Ric Cuzner

    While snorkeling in Thailand certain types of fish would bite off or rip off scab growths from my legs. I had injured my legs in a motorcycle accident. Lots of blood, and scabs afterwards. While snorkeling I could feel fish nipping my legs. Some would cut skin cells painlessly, others would tear or rip skin or scabs. When I would leave the ocean I had trickles of blood down my legs, mostly from where I had scabs.
    Some shops in Thailand offered tourists a fish cleaning spa. People sat with their feet in small baths while fish scraped off dead skin cells.
    So it isn’t just pirahnas that scrape fish scales from fish.

  4. sam davies

    How come you didn't do a full episode on this explaining the differences in how these fish can and why "normal" fish can't eat scales what about the scale rainy fish has evolved other then there mouth to make eating scales possible etc

  5. Caffiene Kitty

    When I was a kid I had "kissing gourami" which I was told couldn't have other fish in their tank because they would 'suck the scales right off of them'. I just googled now and it doesn't say anything about them being scale eaters though, so I now wonder if this was just something my mom told me so I wouldn't ask for more fish. XD

  6. Ok Boomer!

    I was swimming in a little lake in Michigan, and some unknown fish almost bit my left nipple odd. I had blood streaming down my chest.

  7. Crystal L

    My dad used to keep piranha. They did this occasionally even though they were well fed. They would also occasionally pluck out each other's eyes. Every once in a while they would single one out to kill for seemingly no reason. You could tell it was coming if one of them started hanging out on the opposite side if the tank for a day or 2. They were fed daily so none of this was due to lack of resources.

  8. Olof Ekström

    should make an episode about the whole gamut of weird eaters among the cichlids of the rift lakes – scale eaters, chin biters, fin biters, and the mythical eye biters…

  9. Jarno Mikkola

    More peaceful ? Talk about a cannibal that just decided to just skin you rather than kill you. Or punch you in the face to get your blood. Yes, the scale might be easier to rip off than if it were skin, but I bet it still hurts and feels as bad as mosquito bites, and probably has similar overall health consequences, while being at the same scale. Which means it's worse than mosquito biting a human, because the mosquito is so much smaller than human. And people still swat the little buggers. I wonder why.

  10. Eneov

    You have to wonder why it is that some people download a video that is purely factual, why is it that someone doesn't like fishes that eat scales? Are you a fish? Did you get your scales stolen?

  11. Christopher Martin

    Ah, but what about the most fantastic and best scale-eater of all, the scale-eating pupfish??? Cyprinodon desquamator!!!!!!!!!!!!!!
    http://ib.berkeley.edu/labs/martin/

  12. MrShaun

    Not a fan of the way this host looks. For me it was a distraction for the interesting content in the video. She has a great speaking voice for it, and she geniuinly seemed knowledgeable about the subject. For me the whole “look” was just a unnessesary distraction. Otherwise great vid.

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