Yes, There Is Melatonin in Fish: A Complete Guide

November 21, 2025 •

4 min read

Melatonin is a well-known hormone regulating sleep cycles, and fish, like most vertebrates, produce it internally. Studies show that not only do fish contain melatonin, but eating certain types, particularly oily fish like salmon, can improve sleep quality due to their nutritional profile.

Quick Summary

Fish naturally produce melatonin to regulate their biological rhythms. While present in fish tissue, other nutrients like omega-3s and vitamin D may play a more significant role in seafood's sleep-promoting effects for human consumers.

Key Points

Endogenous Production: Fish naturally produce melatonin in their pineal gland, retina, and gastrointestinal tract to regulate their circadian rhythms.
Dietary Source: Fish meat contains residual melatonin, but the quantity is significantly lower than in certain plant-based foods, such as pistachios or tart cherries.
Sleep Benefits via Other Nutrients: The link between eating fish and better sleep is primarily attributed to other compounds like omega-3 fatty acids, tryptophan, and vitamin D, which support sleep regulation.
Fatty Fish Content: Oily fish such as salmon and sardines are particularly beneficial for sleep health due to their high content of omega-3 fatty acids.
Aquaculture Use: In fish farming, melatonin is studied for its effects on growth, reproduction, and stress response in fish, highlighting its physiological importance.
Comparative Concentration: When considering dietary melatonin intake, nuts like pistachios provide a much more concentrated dose than fish.
Comprehensive Approach: For improved sleep, focusing on a balanced diet rich in various nutrients is more effective than relying solely on the melatonin content of fish.

Fish Naturally Produce Melatonin

Melatonin is often referred to as the "sleep hormone" in humans, but its role extends across the animal kingdom. In fish, melatonin is produced primarily by the pineal gland, and also in other areas like the retina and gastrointestinal tract. This internal production is tied to their circadian rhythm, with higher concentrations occurring at night and lower levels during the day. For fish, this hormonal cycle helps regulate various physiological processes, including reproduction, growth, and migration.

Unlike in mammals, where the pineal gland is the primary source, fish have multiple sites for melatonin synthesis. This production is highly responsive to changes in light and darkness, allowing fish to synchronize their metabolism and behavior to environmental cues. For instance, a study on Atlantic salmon found that circulating melatonin levels were inversely related to light intensity, with the duration of the nocturnal increase matching the length of the night.

Melatonin in Fish Tissue

While fish produce melatonin for their own biological functions, residual amounts are also found within their edible tissue. Research has detected melatonin in the gastrointestinal tract and muscle tissue of various fish species, suggesting that consuming fish can contribute a small amount of dietary melatonin. However, compared to some plant-based foods like pistachios or walnuts, the concentration of melatonin in fish meat is relatively low.

Fish as a Dietary Source of Melatonin and Sleep-Supporting Nutrients

Although the direct melatonin content might not be high, consuming fish, especially fatty fish, is still associated with better sleep outcomes. This is likely due to the synergistic effect of other nutrients present in fish that are crucial for sleep regulation. These include:

Omega-3 Fatty Acids (EPA and DHA): Oily fish like salmon and sardines are rich in omega-3s, which play an important role in the secretion of serotonin, a precursor to melatonin. Low levels of DHA, one type of omega-3, have been linked to shorter sleep duration.
Vitamin D: Many fish, including salmon, are excellent sources of vitamin D. Higher vitamin D receptor expression has been observed in brain regions involved in sleep regulation, indicating its potential role in modulating sleep.
Tryptophan: This essential amino acid is a precursor to serotonin and, subsequently, melatonin. Fish provide high-quality protein rich in tryptophan, which can aid in the body's natural production of sleep hormones.

Comparison of Melatonin in Fish vs. Other Foods

To put the melatonin content of fish into perspective, it helps to compare it to other common food sources. The following table highlights the differences, showing that while fish are a decent source among animal products, they are not the most concentrated source of this hormone.


Food Category	Examples	Melatonin Content (per 100g)	Primary Sleep Benefit	Source	Notes
Fish	Salmon, Sardines	~3.7 ng/g (salmon)	Provides melatonin, omega-3s, and vitamin D for holistic sleep support.	Scientific Studies	Oily fish contain higher levels.
Other Animal Products	Eggs, Milk	~1.54 ng/g (egg), ~0.12 pg/mL (milk)	Eggs offer protein and vitamin D; milk provides tryptophan and melatonin.	WebMD, Scientific Studies	Milk levels can vary based on milking time.
Nuts	Pistachios, Walnuts	~233,000 ng/g (pistachios)	Very high in melatonin, plus healthy fats, magnesium, and B6.	EatingWell, WebMD	The most concentrated dietary source.
Fruits	Tart Cherries, Pineapple	~135 ng/g (cherries), ~0.28 ng/g (pineapple)	Cherries significantly increase melatonin levels; pineapple boosts serotonin and tryptophan.	WebMD, Scientific Studies	Tart cherry juice is a popular sleep aid.
Grains	Corn, Rice, Oats	16–2034 ng/g (corn)	Good sources of melatonin and tryptophan.	Scientific Studies	Varies by cultivar and processing.

The Role of Melatonin in Fish Health

In aquaculture, melatonin is a molecule of significant interest, not for human consumption, but for its effects on fish health and reproduction. Experimental studies have shown that exogenous (added) melatonin can influence fish growth, immune responses, and the timing of reproductive cycles.

Growth: Some studies have shown that controlled melatonin administration can influence growth rates in fish, with different dosages having varying effects.
Reproduction: As a key mediator of photoperiodic information, melatonin helps regulate the seasonal reproductive cycles in fish. The timing and duration of melatonin production influence gonadal maturation.
Stress and Immunity: Melatonin has antioxidant properties and has been shown to boost the immune system in fish. It can help reduce oxidative stress and inhibit the increase of cortisol levels in fish exposed to acute stress.

Overall, the presence and function of melatonin in fish are well-documented areas of scientific study. However, its role as a dietary component for humans is a separate matter, where the total nutritional profile of the fish is more influential than its residual melatonin content alone. A balanced diet incorporating various nutrient-rich foods, including fatty fish, remains the best approach for promoting healthy sleep patterns. The conversation surrounding food and sleep is complex, and consuming fish is just one piece of the larger picture, offering multiple benefits beyond just melatonin. For more insight into the physiological effects of fish consumption on sleep, refer to studies like this one on marine fish intake and sleep quality.

Conclusion

In conclusion, yes, there is melatonin in fish, as they are vertebrates that produce the hormone internally to regulate their own biological rhythms. While fish meat contains some melatonin, it is not considered the primary source of the hormone for humans, especially when compared to plant-based foods like nuts and tart cherries. The significant connection between fish consumption and improved sleep quality is more likely due to a combination of other powerful nutrients, including omega-3 fatty acids, vitamin D, and tryptophan. Including fatty fish like salmon and sardines as part of a balanced diet can provide comprehensive benefits for your sleep health and overall well-being. Ultimately, focusing on a diverse diet rich in various vitamins and minerals is the most effective strategy for promoting a good night's rest.

Frequently Asked Questions

Oily fish, like salmon and sardines, are noted for having higher levels of melatonin compared to other fish and meats, as well as providing valuable omega-3 fatty acids.

Eating fish, particularly fatty fish, has been associated with improved sleep quality and shorter sleep latency. However, this effect is likely due to a combination of nutrients like omega-3 fatty acids and vitamin D, rather than just its melatonin content.

While consuming fish contributes some melatonin, the amount is likely too low to have a direct sedative effect on humans. The overall nutritional benefits, especially from omega-3s, are what primarily contribute to its sleep-promoting effects.

In fish, melatonin is a vital time-keeping hormone, produced by the pineal gland and retina, that helps regulate their daily and seasonal biological rhythms in response to light and darkness.

Yes, many foods contain more melatonin than fish. Certain nuts, like pistachios and walnuts, as well as fruits like tart cherries, are known for their relatively high melatonin content.

Similar to other heat-sensitive compounds, the melatonin content in fish could potentially be affected by the cooking process, though the impact is not widely studied. The residual levels are low to begin with, so relying on other nutrients is a more robust strategy for sleep support.

While not a direct 'sleep aid' in the way a supplement is, incorporating fish into your diet, particularly fatty fish, can contribute to overall better sleep health by providing essential nutrients that support the body's natural sleep-wake cycle.