Choosing Fish

What are the issues?

Fish is renowned for being a nutrient-rich food, a staple protein source, and a key component of a healthy diet. As naturopathic doctors, we encourage people to eat more fish. But there is a growing awareness that there are conflicting issues about the best choices when shopping for fish.

As global demand for seafood grows, there are two primary sources for consumers: wild-caught fish and farm-raised fish. While both provide nutrition, the methods of production and the implications for health, environment, and sustainability differ substantially. We hope to empower you to make informed choices for your health and the planet.

Farmed fish are bred and raised in controlled environments such as tanks, ponds, or ocean pens. Aquaculture, the practice of farming fish and other aquatic organisms, has been with us for many centuries – you can still see the ancient structures built by Hawaiians! Aquaculture has grown rapidly over the past few decades and now supplies more than half of the world’s seafood. Common farmed species include salmon, tilapia, catfish, trout, and shrimp.

Wild fish, on the other hand, are caught from their natural environments—rivers, lakes, and oceans—using a variety of fishing methods such as nets, lines, or traps. Examples include wild-caught salmon, cod, haddock, tuna, and sardines.

Wild fish feed on a diet native to their ecosystem, leading to leaner flesh and often higher nutrient density. Fatty species like salmon and sardines typically contain higher levels of omega-3 fatty acids (EPA and DHA), which are beneficial for heart and brain health. Wild fish are less likely to be exposed to antibiotics, artificial colorants, and many contaminants used in aquaculture. 

Many wild fish populations are under threat due to overfishing, leading to depleted stocks and, in some cases, species endangerment. Wild fishing methods may result in bycatch (unintended species caught) and habitat destruction, negatively impacting marine ecosystems.

In larger predatory species like tuna (the top of the food chain), wild fish may accumulate higher levels of environmental pollutants such as mercury, polychlorinated biphenyls (PCBs), and dioxins. 

Farmed fish provide a consistent, year-round supply of seafood, helping bridge the gap between demand and what wild fisheries can sustainably provide. Farming fish can reduce the depletion of overfished wild populations, and help preserve biodiversity.

However, high-density farming conditions may facilitate the spread of diseases and parasites among fish, often requiring the use of antibiotics or other chemical treatments.

In addition, there are significant environmental impacts. Fish farms, especially open-net pens in the ocean, can cause water pollution from waste, uneaten food, and chemical runoff, and may lead to habitat degradation. Some farmed species (like salmon) require feed composed partly of wild-caught fish, raising concerns about the sustainability of feed sources. In addition, overuse of antibiotics and other chemicals in aquaculture can contribute to the development of antibiotic-resistant bacteria and contaminate water.

The nutritional profiles of farmed and wild fish vary depending on species, diet, rearing conditions, and location. Key considerations include:

• Omega-3 Fatty Acids: Wild salmon generally has more omega-3s per serving than farmed, but certain farmed fish are now bred or fed to boost omega-3 content.

• Calories and Fat: Farmed fish, due to controlled diets and less physical activity, often have higher fat content and slightly more calories than their wild counterparts.

• Protein: Both wild and farmed fish are excellent protein sources, but wild fish may be marginally higher in protein per serving.

• Contaminants: Wild fish may contain more mercury and persistent organic pollutants (POPs), while farmed fish can be exposed to many different chemical residues from farming practices.

How can I make good choices when buying fish?

• Choose seafood from reputable sources with certifications where possible.

• Buy smaller fish that have had less time to accumulate environmental contaminants.

• Vary your seafood choices to avoid putting pressure on a single species or region.

• Pay attention to advisories regarding mercury and other contaminants, particularly for vulnerable groups (pregnancy, breastfeeding and young children).

• If sustainability is a concern, consult guides such as Seafood Watch or government resources for up-to-date recommendations.

Both farmed and wild fish have important roles in feeding the world’s population and supporting sustainable food systems. Each comes with its own set of benefits and challenges. Wild fish often offer superior flavor and nutritional density and may support traditional livelihoods, but they are also vulnerable to overfishing and environmental contamination. Farmed fish can help relieve pressure on natural stocks and provide a steady food source, yet they require careful management to mitigate environmental and health risks.