The National Health Service suggests that “A healthy, balanced diet should include at least 2 portions of fish a week, including 1 of oily fish.”

This is because fish and shellfish are good sources of many vitamins and minerals.

  • Oily fish (like herring, pilchards, salmon, sardines, sprats, trout and mackerel) are high in long-chain Omega-3 fatty acids, which can help to keep your heart healthy, and a good source of vitamin D.
  • White fish (like Cod, haddock, plaice, pollock, coley, dab, flounder, red mullet, gurnard and tilapia) are good sources of low-fat protein.
  • Shellfish (eg. prawns, mussels, scallops, squid, mussels, oysters, crab and langoustine) are low in fat and a source of selenium, zinc, iodine and copper.

Healthline is also enthusiastic about the health benefits of eating fish, and lists these benefits:

  • It’s high in many important nutrients.
  • At least one serving of fish per week has been linked to a reduced risk of heart attacks and strokes.
  • It’s high in Omega-3 fatty acids, which is essential for brain and eye development.
  • Intake is linked to reduced mental decline in older adults.
  • Fish is an excellent source of vitamin D.
  • Fish has been linked to a reduced risk of type 1 diabetes and several other autoimmune conditions.
  • People who eat more fish have a much lower risk of Age-related Macular Degeneration (AMD).
  • Eating fatty fish like salmon may improve your sleep.

The Risks of eating fish

Although Healthline is very positive about the benefits of fish, they do caution that some types of fish have high levels of mercury, and that raw and uncooked fish may contain harmful micro-organisms.

The NHS website has these warnings:

  • For certain types of fish, there are recommendations about the maximum amount you should eat.
  • Oily fish and some white fish contain pollutants.
  • Adults should have no more than 1 portion of shark, swordfish or marlin a week, because of the high levels of mercury.
  • Fresh tuna is also high in mercury, so limit yourself to two portions a week.

The NHS website also notes the Food Standards Agency (FSA) advice that older people should avoid eating raw or lightly cooked shellfish, to reduce their risk of getting food poisoning.

Farmed fish versus wild fish

You may think that the fish caught in the wild are more exposed to toxins like mercury and PCBs than those reared in the controlled conditions of fish farming.

But it’s not as simple as that.

The farmed fish you eat can contain mercury, PCBs, DDT etc. in just as large a quantity as wild fish, dependent on the water they are reared in and the food they are given.

Here’s a typical ingredients list for the food pellets given to farmed trout:

  • Grains
  • Fish Meal
  • Porcine blood cells
  • Hydrolyzed Feather meal
  • Astaxanthin pigment for flesh coloration

Can you believe it? Trout are being fed pig’s blood? Feathers? Coloring?

Worst of all possibly is that farmed fish are often given hormones and antibiotics to improve growth and reduce infection, and no doubt traces of these end up in what humans then eat.

In an article in “A 2003 report from the Environmental Working Group (EWG) found that seven out of ten farmed salmon purchased in grocery stores in San Francisco, Washington, DC, and Portland were contaminated with cancer-causing polychlorinated biphenyls (PCBs) at “levels that raise health concerns. Additionally, farmed salmon has been found to contain toxic chemicals methylmercury and dioxins.”

An article from the Cleveland Clinic has this to say about farmed versus wild salmon:

  • Risky pollutants: PCB levels are five to 10 times higher in farmed fish than in wild fish.
  • Cancer-causing chemicals: Both wild and farmed salmon come with risk if eaten in large quantities.
  • Unsafe contaminants: Both wild and farmed salmon contain contaminants, but wild salmon has lower levels.
  • Concern about antibiotics: Farmed salmon comes with uncertainty about antibiotic use.

In Summary

Ideally, there would be regular tests on toxin levels in the fish you buy, with results available to you. But as this is rather unlikely to happen, for the foreseeable future, if practicable, you should choose wild fish from sea areas that aren’t polluted, or farmed fish where there’s an established track record of safe and healthy management of the fish.

If you do buy farmed fish, go organic, to avoid those added hormones and antibiotics, and some of the pollutants in the water and food.