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Why Do My Tomatoes Like Fish – The Odd Phenomenon

Biting into a fishy-tasting tomato can be pretty surprising and most likely displeasing. This is an interesting phenomenon that home gardeners, chefs, and tomato eating enthusiasts may or may not have experienced. While a fishy tasting tomato may not be the most common occurrence, it is certainly an oddity that is theorized by some to be a result of methods of growing, fertilizing, harvesting, or processing the tomato. So when this strange fishy flavor is present after biting into a homegrown tomato, store bought tomato, or tomato dish, many wonder why my tomatoes taste like fish?

There are several theories as to why tomatoes sometimes taste like fish. Although there is not much scientific research to back up these theories, ideas for where this fishy tomato flavor comes from include: fish elements in fertilizers, genetic modifications of tomato varieties, underripe tomatoes, overripe tomatoes, and overcooking of tomatoes in recipes.  

Read on to learn more about fishy-tasting tomatoes and other facts related to tomato varieties and their flavors.

4 Theories As To Why Tomatoes May Taste Fishy

A fishy tasting tomato is no fun, but we do have a few theories as to why this is.


Fertilizers containing fish elements are quite popular with at-home gardeners. Fish fertilizers are a healthy source of nitrogen and contain phosphorus and potassium, all of which are healthy for soil and the growth of tomato plants. I am personally fond of a fish hydrolysate fertilizer made locally in my area that has shown clear benefits in my tomato plants’ growth and harvests.  

There are many types of fertilizer options that contain fish bone meal or are a hydrolysate like the one I use. While these fertilizers are very beneficial to plant development, it is theorized that using them when the tomato fruit is developing or near harvest could lead to tomatoes acquiring a fishy flavor.

While this is not a consistently reported outcome, the connection has been made by some gardeners that the use of fish-based fertilizers resulted in their fishy-tasting tomatoes. The best practice to avoid altering the flavor of your tomatoes with any fertilizer is to stop using said fertilizer 2 – 3 weeks before your first harvest.  

Genetic Modifications

Genetically modified tomatoes are not new, but research is finding out more and more about these lab created varieties of tomato plants. Genetically modified tomatoes are most often found in bulk selling environments like chain grocery stores and found less frequently in home gardens.

There has been debate about whether or not fish genes were used in the genetic modification of some tomato varieties. However, several researchers nix the theory that fish genes in genetic modification could lead to fishy tasting tomatoes.

While the debate remains unresolved, it’s safe to say that if your tomato tastes like fish due to a genetic modification, it was probably bought at the grocery store and not grown in your at home garden.  

Underripe or Overripe 

Most of us know there is a sweet spot of ripeness when eating tomatoes. While it is acceptable and sometimes beneficial to ripen tomatoes off the vine, some gardeners theorize that eating an underripe or overripe tomato could lead to a fishy tomato flavor. Tomatoes overripe to the point of mushiness have especially been identified as fishy tasting by some.  

There are thousands of tomato varieties, many of which ripen to a different color than the typical fire engine red that is often thought to be the most common.

Knowing the characteristics of the variety of tomato you are growing well, including how it should look and feel at prime ripeness, is imperative to getting the highest quality flavor from your tomatoes. While not scientifically proven, some still claim that eating an underripe or overripe tomato has left them with an unexpected fishy flavor.


As you may imagine, an overcooked tomato can have a similar taste to an overripe tomato. Some chefs and food enthusiasts have theorized that overcooking fresh tomatoes can lead to a fishy flavor; as all avid tomato eaters know, there are many ways to use tomatoes in cooking.

If creating a pasta sauce, the chef knows to cook those tomatoes for hours until they simmer down to create a hearty, tasty sauce. However, if adding tomatoes to a dish to maintain their shape, consistency, and flavor of freshness, it’s essential to cook them briefly as one of the final ingredients.

Some have identified that tossing the tomatoes into this recipe too soon can sometimes result in an overcooked fishy flavor. There is also a theory that this is more common with cherry tomatoes than in other varieties.  

Odd Flavored Tomato Varieties

We’ve learned that genetics, ripeness, and cooking can affect the flavor of tomatoes. The variety of tomatoes you are growing can also affect their flavor. Here are some of the most distinctly flavored tomato varieties:

Knowing the typical characteristics of the tomato variety you choose to grow can help with surprises in flavor at harvest time.  

Why Tomato Flavors Differ

The combination of sugar and acidity in a tomato leads to the variations in flavor. Tomatoes are often categorized as either tart, sweet or savory. Tart tomatoes typically have more acidity, and sweet tomatoes contain more sugar.

Many prefer the most common savory tomato flavor is a half and half balance of tart and sweet or acid and sugar. Here is a breakdown of how the color of your tomatoes may connect to their flavor:

In addition to the variations in tomato flavor that have already been shared, cherry and grape tomatoes are almost always sweeter than larger tomato varieties, regardless of color.  

Final Thoughts on Tomato Flavor

When contemplating the peculiar or satisfying flavor of your tomato, one thing is that human taste buds often differ from person to person. Sometimes we interpret flavors of the same fruit, vegetable, or prepared dish differently.

The perceived flavor that each individual identifies is a combination of taste and smell, which leads to these differences in interpretation. Whether your tomato tastes funny, interesting, or delicious, it’s always recommended to get a second opinion before deciding on an individual tomato, tomato variety, or tomato recipe’s flavor.  

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