Demystifying Dory: John Dory vs. Pangasius
When people ask, "is dory fish high in mercury?" the question is often rooted in a simple but crucial point of confusion: the name "dory" can refer to multiple, distinct species of fish sold in the market. The authentic John Dory (Zeus faber) is a wild-caught marine fish prized for its delicate flesh, but a farmed Asian catfish species, Pangasius (Pangasius bocourti), is commonly and sometimes deceptively sold as "Cream Dory" or "Pacific Dory",. Understanding the difference is key to assessing any health risks, including mercury exposure.
John Dory (Zeus faber): A Low-Mercury Option
The genuine John Dory is a demersal, or bottom-dwelling, coastal fish found in the eastern Atlantic and Mediterranean,. As a predatory fish, it does contain some mercury due to biomagnification, the process where mercury concentrations increase up the food chain. However, it is not an apex predator like a swordfish or shark, and its mercury content is typically considered low to moderate, well within recommended safety guidelines for regular consumption,. A study testing a type of smooth dory from New Zealand, for example, found mercury levels placing it in the "best and good choices" category.
John Dory is a nutritionally sound choice, offering a healthy dose of lean protein, vitamins (including B12), and minerals like iodine, selenium, and phosphorus,. Its moderate omega-3 fatty acid content contributes to brain and cardiovascular health,.
Cream Dory (Pangasius): The Catfish Imposter
The fish sold widely as "Cream Dory" is in fact Pangasius, a fast-growing, farmed catfish primarily from Vietnam. This species has received criticism in the past regarding mass-production conditions, but its mercury content is typically extremely low,. As a bottom-feeding, non-predatory fish with a shorter lifespan, it does not accumulate significant levels of mercury. The FDA and EPA classify most catfish as a "best choice" due to their low mercury content.
Like John Dory, Pangasius is a good source of protein and other nutrients. Its lower price point makes it an affordable and popular choice for many consumers. For health-conscious individuals, particularly those limiting mercury intake like pregnant women and young children, Pangasius is a very safe option from a mercury perspective, provided it is sourced from reputable suppliers adhering to safety standards.
How Does Mercury Accumulation Work?
Mercury is a naturally occurring element that can enter water bodies from both natural events and human activities, such as coal burning. In water, microorganisms convert it into highly toxic methylmercury, which is then absorbed by aquatic life. This compound then bioaccumulates and biomagnifies up the food chain. Larger, longer-lived predatory fish at the top of the food chain, such as shark, swordfish, and certain types of tuna, tend to have the highest concentrations of mercury because they consume many smaller fish over their lifetime,. Fish lower on the food chain, like sardines, salmon, and catfish (Pangasius), have much lower levels.
The Mercury Levels in "Dory" Fish
| Feature | John Dory (Authentic Dory) | Cream Dory (Pangasius) |
|---|---|---|
| Species | Zeus faber | Pangasius bocourti (a type of catfish) |
| Sourcing | Wild-caught, often from the Atlantic and Mediterranean | Farmed, primarily from Southeast Asia (Vietnam) |
| Mercury Level | Low to moderate, | Very low, |
| Food Chain Position | Predator, not an apex predator | Bottom-feeder, lower trophic level |
| Consumption Advice | Safe for regular consumption for most people | A "Best Choice" for frequent consumption |
| Flesh Character | Delicate, sweet, firm white meat | Mild, flaky white meat |
Low-Mercury vs. High-Mercury Fish
To make healthy choices, it's helpful to be aware of the general mercury levels in different fish. The following list is not exhaustive but provides a representative overview based on FDA/EPA advisories,,.
Low Mercury (Best Choices)
- Salmon
- Shrimp
- Canned Light Tuna
- Tilapia
- Cod
- Sardines
- Catfish
- Oysters
- Scallops
- John Dory (low/moderate category)
- Pangasius (Cream Dory)
High Mercury (Avoid or Limit)
- Shark
- Swordfish
- King Mackerel
- Bigeye Tuna
- Marlin
- Orange Roughy
- Tilefish (Gulf of Mexico)
The Importance of Variety and Sourcing
For most people, the health benefits of eating fish—like its omega-3 fatty acids, protein, and minerals—outweigh the risks associated with mercury, especially when choosing low-mercury options. However, individuals in high-risk categories, such as pregnant or breastfeeding women and young children, should be particularly mindful of their choices. The FDA and EPA provide specific guidance for these populations, recommending 2–3 servings of fish from the "Best Choices" list per week. For more detailed information, consult the FDA's guidance on eating fish.
Conclusion
The idea that all "dory" fish is high in mercury is a common misconception stemming from the ambiguous naming of the fish. In reality, the authentic John Dory is a low-to-moderate mercury option, while the more widely available Pangasius, or "Cream Dory," is a very low-mercury species. By distinguishing between these two types and understanding the general principles of mercury accumulation, consumers can confidently incorporate these fish into a healthy, balanced diet while managing any potential risks. Checking with your seafood supplier about the specific species can also provide reassurance.
