The Complex Reality of Eating Fish
For years, the advice has been simple: eat less red meat and eat more fish. It’s seen as lighter, cleaner, better for your heart, and better for the planet. However, when you factor in welfare, environmental damage, and sheer scale, it becomes clear that this choice is one of the most ethically complicated.
In recent months alone, cracks have started to show. New figures revealed that almost 36 million fish died in aquaculture cages over three years, with regulations being ignored at over 75% of sites surveyed. In the UK, there is concern that industrial trawlers are still fishing in supposedly protected waters. Once framed as a “better” option to meat or poultry, fish is now more likely to be described as at “breaking point” or on the “brink of disaster,” exposing just how fragile the system behind it really is.
To be clear, the health case for fish is real. In the UK, official dietary advice recommends eating at least two portions a week, one of them oily. The British Nutrition Foundation (BNF) says these recommendations date back to a 2004 report which found that “the equivalent of two 140g portions of fish per week … had significant health benefits, particularly reducing risk of cardiovascular disease and benefits for maternal health when eaten in pregnancy.”
Fish is rich in protein, iodine, vitamin B12, and selenium, while oily fish provides omega-3 fatty acids and vitamin D. More recent evidence continues to support its role in heart health, and there is emerging research suggesting links to reduced risk of cognitive decline.
In other words, the advice to eat fish isn’t wrong. If anything, most of us aren’t eating enough. Average UK consumption sits at around one portion a week, with oily fish intake particularly low. But the BNF acknowledges that this guidance comes with caveats: “There are likely to be population health benefits of increasing fish intakes, but this needs to be balanced with sustainability concerns.”
Which is where things become far less straightforward. Fish has long been positioned as a cleaner, greener alternative to meat. In reality, the picture is more fragmented. “The question is not ‘fish or meat,’ says Kerry Lyne, Good Fish Guide manager at the Marine Conservation Society. “It is more about understanding where the fish is from, how it is caught or farmed, and the species.”
Some seafood can have a lower environmental impact than meat, but that comparison, crucially, tends to focus on climate – and often on its most flattering metrics. Where beef drives deforestation and methane emissions, fishing brings a different kind of environmental damage – one that is less visible, but no less profound.
Bottom trawling, for example, can remove up to a quarter of seabed life in a single pass and has been likened to clear-cutting the ocean floor like a forest. It also releases an estimated 370 million tonnes of carbon dioxide each year, roughly equivalent to the entire UK’s annual emissions.
Aquaculture, meanwhile, begins to look more like land-based farming. Farmed salmon can generate higher emissions than chicken, and relies on feed made from wild fish, adding further pressure to marine ecosystems. In effect, it carries the impacts of both systems, combining industrial farming with the extraction of wild fishing.
The issue is compounded by what we actually eat. In the UK, just five species – salmon, cod, haddock, tuna, and prawns – account for roughly 80% of seafood consumption. That concentration puts intense pressure on a narrow slice of marine life, even as other, more sustainable species go largely ignored.
Even the systems designed to make fishing sustainable are showing signs of strain. Nearly 40% of England’s seas are designated as protected marine areas, yet between 2020 and 2024, more than 1.3 million tonnes of fish were still caught within them. Critics have described these areas as “protected only on paper,” a phrase that neatly captures the gap between policy and reality.
Environmental Impact of Fishing
370 million tonnes of CO2 released each year from bottom trawling.
The same disconnect is visible in fishing quotas. In the case of North East Atlantic mackerel, scientists recommended a 70% reduction in catches to protect stocks. Governments agreed to cut just 48%.
The result is a system in which sustainability exists more in principle than in practice, something now felt beyond policy circles and into the supermarket aisle. Earlier this year, Waitrose became the first UK retailer to suspend sales of mackerel, long considered one of the more sustainable and nutritious fish, because it “will no longer meet our responsible sourcing requirements,” according to the retailer. “By suspending sourcing, we are reinforcing our ethical and sustainable business commitments, acting to tackle overfishing and protect the long-term health of our oceans.” The supermarket said it would only reintroduce the species once stocks recovered.
If environmental concerns complicate the picture, animal welfare reshapes it entirely. “In the scientific field, it is accepted that fish experience pain and discomfort,” says Lynne Sneddon, a professor at Gothenburg University and an expert on fish health and welfare. Her research has shown that fish respond to painful stimuli in ways that go beyond reflex. “Fish in pain ignore novel, fear-causing objects and do not show normal anti-predator behaviours as their attention appears to be dominated by the pain state,” she says. “Fish are highly intelligent animals, capable of complex behaviours. So fish should be treated as sentient, intelligent beings capable of experiencing pain and discomfort.”
Compared to land animals, fish exist largely outside public view, and, as a result, outside much of the regulatory framework that governs animal welfare. “There are many things that happen during fish farming that would be considered completely unacceptable in land animal farming,” Prof Sneddon says. She points to salmon farming, where fish can be infested with lice that burrow into their skin, causing lesions. Treatments to remove them – including putting them “in water hot enough to cause pain or put in a fast flow of water, which dislodges their skin and scales as well as the parasites” – can themselves cause harm.
“If the public saw a cow or sheep in a field covered with parasites, there would be an outcry,” she says. “But because fish are farmed underwater, it remains out of sight and out of mind.”
Haven King-Nobles of the US-based Fish Welfare Initiative puts it more bluntly. “Fish are not like us … and for the most part feel very distant from us mammalian primates,” he says, which is why “we tolerate certain practices, such as catching fish by impaling a hook through their mouth, that we would never accept with terrestrial animals.”
Then there is the question of scale and the way fish are counted. “Both fish farming and fishing occur on a mind-boggling scale globally,” says Mr King-Nobles. “There’s roughly 100 billion fish on farms right now – that’s about the same number of humans who have ever lived! And with [wild] fishing, we are talking about 1-2 trillion fish killed each year. Unfortunately, these are all rough estimates as these animals are not measured in individuals but in tonnage, which is revealing of what little moral weight we afford them.”
It is a staggering figure, and hard to picture. We tend to think of food in portions: a slice, a fillet, a serving. But with fish, that simplicity rarely holds. Take a standard salmon fillet. On paper, it’s one fish, neatly portioned. In reality, it’s more complicated. Estimates suggest that for every 100g eaten, around 172g of wild fish may have been used as feed – meaning a typical 140g fillet can carry the hidden weight of roughly 240g of other fish behind it.
In other words, several fish may have died for you to enjoy a single salmon fillet. Can you say the same for your steak?
None of this means that fish is uniquely bad, or that it should be abandoned altogether. As the Marine Conservation Society advises, consumers can make better choices by avoiding red-rated species, diversifying what they eat, and choosing options such as UK-caught hake – a more abundant, well-managed stock – farmed trout, which tends to have lower environmental impacts than salmon, and blue mussels, which can actively improve water quality by filtering it.
But navigating that isn’t always straightforward. Labels such as “responsibly sourced” or “sustainably sourced” can be helpful, but they are not a guarantee of best practice. “These claims are often based on a business’s own voluntary sourcing code,” says the Marine Conservation Society’s Kerry Lyne, “and while some companies apply these standards well, data standards vary across businesses.”
Ultimately, the most reliable guide is clear information – what species it is, where it came from, and how it was caught or farmed. “If that information is missing, it becomes much harder to make an informed choice,” she says. “In those cases, we would encourage people to ask the staff, the fishmonger, or the waiter for more details. If that information still is not available, our advice would be to leave it.”
The idea of fish as an easy answer – a simple swap that resolves the ethical and environmental problems of meat – no longer holds. Part of the reason it has persisted for so long is visibility. We drive past fields of cows and sheep. We see chickens in sheds, pigs in pens. Fish, by contrast, exist out of sight – underwater, in cages or in nets – their lives and deaths, and the environmental damage trawlers leave behind, largely hidden from view. And for the most part, we do not consider them sentient enough to be afforded the same protections as more familiar mammals, despite more than 80 studies showing they feel pain just like we do. That distance makes it easier to ignore the scale, the systems, and the trade-offs behind them.
Fish may still be one of the healthiest things you can put on your plate. But until those systems are brought into the open – and held to the same scrutiny as the animals we can see – it will remain one of the most ethically complicated, too.
