Understanding What Are the Disadvantages of Being a Pescatarian?

November 6, 2025 •

3 min read

While often celebrated for its health benefits, a pescatarian diet is not without its potential drawbacks. This article will detail the specific challenges, including risks associated with mercury contamination and high costs, helping you understand what are the disadvantages of being a pescatarian?

Quick Summary

The pescatarian diet has potential downsides, such as exposure to mercury from certain fish and higher costs compared to some diets. It also carries the risk of nutrient deficiencies if not well-planned, along with ethical and environmental concerns regarding fishing practices.

Key Points

Mercury Contamination: Certain large, predatory fish carry high levels of mercury, posing a health risk, especially for vulnerable groups like pregnant women.
Higher Costs: Fresh, high-quality seafood and fish can be more expensive than other protein sources, potentially increasing grocery expenses.
Nutrient Deficiencies: Eliminating red meat can create potential deficiencies in critical nutrients like vitamin B12, iron, and zinc without careful meal planning.
Environmental Concerns: Despite a lower carbon footprint than red meat, overfishing and by-catch in the fishing industry pose significant threats to marine ecosystems.
Ethical Considerations: For some, the ethical debate around whether fish feel pain can be a drawback, leading to moral unease.
Careful Planning is Necessary: A pescatarian diet requires proactive planning to ensure a well-rounded intake of nutrients and to mitigate risks associated with seafood consumption.

The Hidden Costs and Contaminants in a Fish-Based Diet

Transitioning to a pescatarian diet, which includes fish and seafood alongside a vegetarian base, is often seen as a healthier alternative to a meat-heavy diet. While it offers many benefits, it is crucial to understand the potential drawbacks before committing long-term. These can range from health risks associated with mercury and other contaminants to significant financial and environmental burdens. Making an informed decision means weighing the pros and cons carefully, ensuring a balanced approach to nutrition and a sustainable lifestyle.

The Risk of Heavy Metal Exposure

One of the most significant concerns for pescatarians is the potential for mercury exposure. Mercury, a neurotoxin, can accumulate in fish and other seafood. Larger, predatory fish that live longer tend to have the highest levels of mercury. For most healthy adults, consuming fish in moderation according to recommended guidelines poses a minimal risk. However, vulnerable populations, such as pregnant women, breastfeeding mothers, and young children, must be especially cautious and avoid certain types of fish altogether.

In addition to mercury, seafood can sometimes contain other pollutants like polychlorinated biphenyls (PCBs). Responsible fish consumption involves selecting lower-mercury options and sourcing seafood from transparent, sustainable providers.

High-Mercury Fish to Limit or Avoid:

King Mackerel
Shark
Swordfish
Bigeye Tuna
Tilefish

Low-Mercury Fish to Enjoy More Often:

Salmon
Sardines
Shrimp
Catfish
Canned light tuna (skipjack)

Potential Nutrient Deficiencies

While a pescatarian diet provides a good source of protein and omega-3 fatty acids, removing red meat can lead to potential nutrient deficiencies if not planned carefully. Key nutrients to monitor include iron, zinc, and vitamin B12.

Iron and Zinc Challenges

Heme iron, which is found in red meat, is more easily absorbed by the body than the non-heme iron found in plant-based sources. While some fish, like salmon and tuna, contain iron, it might not be enough to compensate for the elimination of red meat. Zinc is also a challenge; it is abundant in red meat and poultry, and while present in some shellfish, legumes, and nuts, dietary planning is essential to ensure adequate intake.

Vitamin B12 Concerns

Vitamin B12 is primarily found in animal products. Pescatarians who regularly consume fish, eggs, and dairy may get sufficient B12. However, for those who eat these products less frequently or in small amounts, B12 deficiency is a real risk. Symptoms can include fatigue and neurological issues. Careful planning and potentially fortified foods or supplements may be necessary.

The Cost and Inconvenience

For many, the cost of incorporating fresh, high-quality seafood into a regular diet can be a significant deterrent. While some types of fish are inexpensive, premium seafood can be costly, leading to a higher grocery bill. Furthermore, sourcing sustainable and low-mercury options requires research and effort, adding another layer of complexity to meal planning.

Environmental and Ethical Considerations

While a pescatarian diet generally has a lower environmental impact than a conventional diet high in red meat, it is not without its own set of concerns. Overfishing is a serious global issue that threatens marine ecosystems. By-catch, the unintentional capture of non-target marine life, also harms ocean wildlife, including dolphins and sea turtles.

For those motivated by ethical concerns for animals, the question of whether fish can feel pain is a complex and ongoing debate. Choosing sustainable seafood is a key responsibility for any pescatarian concerned with their environmental footprint and the health of the oceans.

Comparison of Diets: Pescatarian vs. Omnivore


Feature	Pescatarian Diet	Omnivorous Diet
Mercury Exposure Risk	Present, dependent on fish choice	Minimal (unless consuming specific fish)
Cost	Can be high, depending on seafood selection	Variable; red meat can be more affordable
Nutrient Gaps	Potential for deficiencies in B12, iron, zinc	Lower risk of common deficiencies, if balanced
Environmental Impact	Moderate (concerns with overfishing)	High (land use, emissions)
Protein Sources	Fish, seafood, plant-based foods	Fish, meat, poultry, dairy, plant-based foods

Conclusion: A Balanced Perspective

Ultimately, a pescatarian diet can be a nutritious and health-conscious choice, but it requires mindful navigation of its potential pitfalls. The disadvantages, including the risk of mercury contamination, higher costs, potential nutrient deficiencies, and environmental impacts, are manageable with careful planning and education. By understanding the specific challenges, pescatarians can make informed decisions about their food choices, ensuring they maximize health benefits while minimizing risks. Prioritizing low-mercury, sustainably sourced seafood and actively seeking alternative nutrient sources is key to a successful and responsible pescatarian lifestyle. For more information on seafood sustainability, consult reliable resources like the Monterey Bay Aquarium's Seafood Watch recommendations.

Frequently Asked Questions

No, not all fish are high in mercury. Larger, longer-living predatory fish like swordfish and shark typically have higher levels, while smaller fish like sardines and salmon have much lower concentrations.

Pescatarians can get vitamin B12 from fish and seafood, as well as eggs and dairy products. It's important to include a variety of these foods or consider fortified cereals and supplements if intake is low.

The cost of a pescatarian diet is variable. While staples like canned tuna can be affordable, fresh, high-quality seafood can be expensive, potentially increasing grocery costs compared to a plant-based or standard omnivorous diet.

A pescatarian diet typically has a lower environmental impact than a diet high in red meat. However, it still raises concerns about overfishing, by-catch, and the sustainability of certain fishing practices.

If not properly planned, pescatarian diets may lead to deficiencies in nutrients like iron, zinc, and vitamin B12, which are abundant in red meat.

Pregnant women can be pescatarian but must be very cautious about their fish choices. They should stick to low-mercury fish and adhere to FDA guidelines to minimize risks to the fetus.

To find sustainable seafood, consult resources like the Monterey Bay Aquarium's Seafood Watch recommendations. These guides help identify fish that are caught or farmed in environmentally responsible ways.