This Korean Fish Smells Like Ammonia. So Why Do People Love It?
Korea’s fermented skate can smell shockingly like ammonia. Is it spoiled, fermented—or something in between? Here’s the science and culture behind hongeo.
A Food That Makes Even Some Koreans Nervous
There are Korean foods that almost everyone knows: kimchi, bulgogi, bibimbap.
And then there is hongeo.
Hongeo is fermented skate, and its smell can be so sharp that first-time diners often compare it to ammonia.
Here is the surprising part:
Some Koreans absolutely love it.
Not all Koreans, of course. Hongeo is famously divisive even in Korea. But for devoted fans, the stronger the fermentation, the more interesting the experience becomes.
Korea’s official tourism organization describes fermented skate as a food that produces strong reactions even among Koreans—and notes that experienced diners sometimes begin seeking stronger versions.
But Wait. Isn’t That Fish Rotten?
This is probably the first question many people have.
The answer is more interesting than simply yes or no.
Skates belong to a group of cartilaginous fish that store relatively large amounts of urea in their bodies. After the fish dies, compounds including ammonia are produced as that urea breaks down.
That chemistry is responsible for hongeo’s famously sharp smell.
Research tracking hongeo during fermentation at 10°C found that its pH and ammonia nitrogen increased as fermentation progressed, alongside changes in its bacterial community.
So the smell that tells your brain,
“Do not eat this!”
is part of what hongeo enthusiasts are actually looking for.
Korea’s tourism authority similarly explains hongeo’s pungency through the breakdown of urea into ammonia and other compounds.
Fermented Does Not Mean Risk-Free
There is an important distinction here.
A strong smell does not automatically mean a food is unsafe.
But “fermented” does not automatically mean safe either.
Food safety still depends on proper processing, hygiene, temperature and storage.
That is true for hongeo, and it is true for other fermented foods.
So this isn’t permission to find an old piece of fish in your refrigerator and call it fermentation.
Please don’t.
Koreans Don’t Usually Eat Hongeo Alone
Here’s where Korean food culture makes things even more interesting.
One of the most famous ways to eat hongeo is hongeo samhap—literally a combination of three foods:
fermented skate + boiled pork + aged kimchi.
Put all three into your mouth at once.
The fatty pork softens the experience, while the sour aged kimchi helps balance the pungent skate.
The result is one of the signature food combinations of Korea’s Jeolla region.
And that aged kimchi introduces another Korean idea:
Sometimes, older food is exactly what people are waiting for.
Korea Has Another Famous Relationship With Time: Kimchi
Freshly made kimchi and deeply aged kimchi can feel like completely different foods.
As kimchi ferments, its acidity, aroma and texture continue to change.
Some Koreans intentionally keep kimchi for extended periods because that deeper sour flavor works beautifully in dishes such as kimchi jjigae and kimchi jjim.
Again, age alone doesn’t make food safe.
Properly fermented kimchi can continue fermenting under refrigeration for months, while sliminess or other signs of spoilage are reasons for caution.
The important distinction isn’t simply:
fresh = safe
old = dangerous
It is understanding the difference between controlled fermentation and unwanted spoilage.
And Korea Isn’t Alone
If hongeo sounds extreme, Koreans aren’t the only people who developed a taste for intensely fermented seafood.
Iceland has hákarl, traditionally made from Greenland shark.
Sweden has surströmming, fermented Baltic herring.
Japan has kusaya, fish preserved using a distinctive fermented brine.
In fact, a 2026 scientific study of commercial Icelandic hákarl found it to be an alkaline fermented food with an active and diverse microbial community.
Different countries developed different techniques, flavors and traditions.
But they share an intriguing idea:
Humans learned long ago that time and microorganisms could transform food rather than simply destroy it.
And Korea Isn’t Alone
If hongeo sounds extreme, Koreans aren’t the only people who developed a taste for intensely fermented seafood.
Iceland has hákarl, traditionally made from Greenland shark.
Sweden has surströmming, fermented Baltic herring.
Japan has kusaya, fish preserved using a distinctive fermented brine.
In fact, a 2026 scientific study of commercial Icelandic hákarl found it to be an alkaline fermented food with an active and diverse microbial community.
Different countries developed different techniques, flavors and traditions.
But they share an intriguing idea:
Humans learned long ago that time and microorganisms could transform food rather than simply destroy it.