Why Does Coffee Smell Like Fish? (5 Reasons Explained)

One of the reasons why coffee is loved by many is its rich aroma. The bitter yet sweet smell of brewing coffee can help you feel relaxed and energized simultaneously. In fact, the scent of the coffee makes the whole experience better. But sometimes, the smell of coffee isn't what you expect. Instead of the rich aroma, you get an odd, stinky odor that smells like fish.  

In this article, we will discuss why does coffee smell like fish and how you can get rid of this smell to have a better coffee experience.  

1. Roasted Immature Green Beans  

Coffee comes from a plant and isn’t naturally brown or dark-colored. The fruit of the coffee plant, also known as coffee berry, matures from green to red. To make good coffee beans, you need to wait for the fruit to ripen and achieve a deep red color. If you don’t wait for them to mature and harvest these under-ripe fruits, they will produce low-quality coffee beans. Roasting these immature beans will create a fish-like aroma instead of a rich and flavorful smell.  

In addition to using under-ripe coffee berries, growing a coffee plant in an unsuitable environment can also lead to having immature green beans. The coffee plant should be grown in tropical climates with no frost, ample sunshine, and water. If the plant doesn’t have all three of them, it will bear low-grade fruit, resulting in beans that smell like fish.  

Unfortunately, as consumers, we wouldn’t be able to tell whether or not the beans are harvested immaturely or grown in an unstable environment. The only way we will know is if the coffee smells or tastes odd. That's why you should only buy coffee beans from trusted suppliers to ensure you get the best quality you can find.  

2. Oxidation During Storage 

Have you ever bought good coffee beans from reputable brands only to discover that the coffee smells or tastes like fish? Of course, it's natural to think that the brand may not be as good as it claims to be. But most of the time, this fishy smell doesn't come from the beans themselves but rather from how you store them after buying them.  

Exposing your coffee beans to heat and moisture can cause oxidation, resulting in stale coffee beans. When your beans become stale, the taste and smell are affected. So, don't blame the coffee manufacturer right away. Ensure that you practice good storage. Only use an airtight container and never refrigerate your coffee grounds or beans. Refrigerating them allows the beans to absorb the odor and flavor of what’s in your fridge.  

But in some cases, the cause of the fish smell may not be entirely your fault. Sometimes, manufacturers don’t have good storage practices between roasting and bagging, which can cause some oxidation. However, this is out of your control, so the best way is to ensure that you store your beans properly.  

3. The Hygroscopic Nature Of Coffee Beans 

To get coffee beans, the coffee berries are sun-dried after harvesting. This reduces their moisture content, but it doesn’t stop there. After drying the berries, the beans from the berries are also dried, reducing the moisture even more. The beans are further dehydrated during the roasting process, which leads to the first crack in the wall of the beans.

Later in the process, a second crack will occur due to the water being extracted from them. Because of this process, the coffee beans become “thirsty” or hygroscopic.  

But what does hygroscopic mean? When a substance is hygroscopic, it absorbs moisture from the air and aroma from its surroundings. Coffee is highly hygroscopic, which means that beans exposed to unsavory flavors will end up in your cup of coffee.   

But coffee being hygroscopic is not always a disadvantage. Because of this nature, coffee beans act as a natural air deodorizer. If there is any funky smell in your fridge and drawer, toss in some beans, and you’re good to go.  

4. Improper Storage  

Again, don’t just leave your coffee beans lying around your kitchen. It’s natural to think that you can keep coffee beans in the pouch that comes with it, but most of the time, they don’t seal properly. This could allow your beans to absorb any aroma around them that may contribute to their fishy smell and taste.

So, always store them in airtight jars or containers instead of their original packaging. You can still use the pouch that comes with them, but only if they come in resealable packs.  

5. Unclean Equipment 

Another reason your cup smells and tastes like fish is using dirty coffee makers. If you don’t clean your equipment regularly, oils will build up around it and can cause your cup to taste and smell weird. So, even if you are using the best coffee beans, you will still end up with a bad cup if you have an unclean coffee maker.

To prevent this, regularly clean your coffee makers. You can even use equal parts of vinegar and water to descale your coffee maker further and ensure that everything is squeaky clean.  

If you're also grinding your own beans, make sure the coffee grinder is regularly clean to prevent stale grinds from combining with your freshly ground coffee.  

Why Does Coffee Smell Like Fish? (5 Reasons Explained)

How To Get Rid Of Fish Smell In Your Coffee? 

If your coffee smells like fish, there’s nothing much you can do with the beans. There’s really no way of getting rid of this odor, especially if the processing and roasting process has caused this aroma. If you can’t stand the fish smell in your coffee, the best way to deal with this is to dispose of the coffee beans or reuse them as a deodorizer.  

However, several ways can help you prevent this from happening. First, only buy coffee beans from reputable manufacturers. Next, store them in proper containers and ensure that heat and moisture won’t get in them.

As much as possible, seal the container right after getting coffee to ensure that it won’t absorb any of the aromas from the surroundings. Lastly, clean your coffee equipment after every use.  

coffee before and after

Why Does Coffee Sometimes Taste Like Fish? 

If your coffee tastes like fish, it’s natural to blame your coffee beans. But it’s not always the beans and other factors that can affect your cup. For instance, you might be using contaminated water. Remember, a cup of coffee is 98% water.

Any chemicals in the water you’re using can contribute to the taste of your coffee. Make sure you only use filtered or bottled water.  

Another reason that could affect the taste of your coffee is the equipment you use. Ensure that it’s properly cleaned. Your coffee cup can also make your coffee taste like fish. If you’re using the same sponge for your plates and cups, there’s a possibility that the fish taste is transferred to your cup. 

coffee about to be tasted

Common Coffee Smells Questions 

Can coffee go bad? 

Coffee beans don't go bad like bananas or apples. However, they will lose quality over time. For brewed coffee, it will start to taste bad after 30 minutes or when the cup begins to cool down.  

How do you tell if your coffee is spoiled? 

Coffee doesn’t get spoiled. However, rancid, mildewy, or moldy smell from coffee often means that the coffee has lost its quality and should be thrown out.  

Can old coffee give you food poisoning? 

No, coffee won’t give you food poisoning because it doesn't spoil or go bad. Old coffee will only taste bad but won’t harm your body.  

What does it mean when coffee tastes sour? 

The sour taste of coffee comes from bad brewing and bad beans. Under brewed coffee will taste sour and acidic. At the same time, under-roasted beans and beans that are old and stale will produce sharp, lemony flavors.  


Conclusion

If your coffee smells like fish, no need to panic. This is a regular occurrence, and most of the time, it won’t affect the taste of your cup. If you can’t stand the smell, try switching to a different brand or storing your beans properly to prevent them from having this fish smell again.