Why dogs should not eat fish

Jonathan Self

At Honey’s we have always taken a strong stand against feeding fish to dogs. We offer no fish-based formulas and until fishing is much more sustainable, we never will (with one exception: for dogs with serious medical issues who have few or no other dietary options). In the Honey’s ‘Ingredients Policy’, we provide only a brief explanation as to why we are so anti-fish. Therefore, I thought it might be useful to go into a little bit more detail.

The health risks associated with fish.

Everyone is always talking about the benefits of feeding fish. True, it is packed full of protein, omega-3 etc. etc.. But it also comes with some potential health risks.

For wild fish the main issue is mercury poisoning. This is what Harvard University has to say on the topic:

Generally speaking, depending on the amount of consumption, fish like swordfish, shark, and certain kinds of tuna—large fish that eat a lot of smaller fish—have higher levels of methylmercury (the only form of mercury to bioaccumulate in the human body). At very high exposures, this can lead to fatigue, muscle weakness, and dizziness and damage organs like the kidneys and liver. Chronic low-level exposure to methylmercury has also been shown to impair brain function.

Overall, Harvard thinks the risk is relatively low. Still, they do cite two US legal cases:

Mercury poisoning from fish does occur. One legal case—centred around actor Jeremy Piven was connected to his alleged mercury poisoning from eating too much sushi. In that case, Piven apparently ate sushi twice a day for years according to his doctor. In a medical case involving Richard Gelfond, he too ate significant amounts of fish in the service of eating a healthier diet. In his case he continues to suffer aftereffects and symptoms, even after he changed his diet to remove the relevant fish from his diet.

And they make another interesting point:

Unfortunately, as the oceans warm due to climate change, there’s research led by Elsie Sunderland (who also teaches at Environmental Health Risk) to suggest that certain kinds of fish in certain environments… now have increased mercury levels. Thus, the levels, and the recommendations, may change over time, and it’s critically important to try and remove mercury and carbon dioxide from the environment. Global warming may act as a sort of wild card, throwing off existing numbers and changing the makeup of fish’s food sources—particularly for large, predator fish. Smaller fish, and vegetarian fish, have less risk of exposure.

So, what about farmed fish? Dana Hunnes, a senior dietitian at UCLA Medical Centre, and an adjunct assistant professor at the UCLA Fielding School of Public Health, says:

One of the biggest concerns with farm-raised fish is its potential to contain industrial chemicals, including terephthalic acid (TPA) and polyvinyl chloride (PVC). Fish raised in farms may also contain chemicals used to ‘improve’ their colouring (e.g. the salmon you buy that appears ultra-pink), which could have an impact on our health. Because of the conditions in which most farmed fish are raised, microbial contamination of their habitat could also pose a health threat to us and to wild populations of fish. And then there’s the question of the antibiotics. Just as there are health concerns over antibiotics used in livestock, such as chickens and cattle, farmed-raised fish also are fed antibiotics, which we ingest when we consume fish. Farmed fish are generally ‘grown’ as monocultures – or a single species of fish. Depending on the species of fish, they may be reared within a huge netted system in the ocean, in a fjord, or even in a freshwater pond. Most farmed fish are grown in nets that are overcrowded, which can pose problems. The population can become infested with sea lice, or other microbes, due to their congested living conditions. Diseases can spread more easily in a population of a singular species of fish. Farmed fish are typically fed an unvaried diet – usually, a fish feed or fish pellets that contain ingredients like wild fish, certain nutrients, colouring, and even antibiotics.

There are some other health risks to consider. A recent study by Brown University found that people whose typical daily intake of fish was 42.8g (equivalent to about 300g per week) had a 22 per cent higher risk of malignant melanoma (skin cancer) than those whose typical daily fish intake was just 3.2g.

Obviously, there is a difference between people and dogs. Nevertheless, with regard to mercury and the other industrial chemicals mentioned above it seems to me that the risk is very similar.

(As a side note, some dogs do develop allergic dermatitis from raw fish and can’t handle the bones which are small and sharp and this should also be watched out for if feeding fish.)

The environmental damage done by fishing

The second reason why Honey’s does not have fish on the menu is environmental. The ocean covers over 70% of our planet. It provides more than half the oxygen we breathe and absorbs nearly a third of our carbon emissions. It is no understatement to say that the world’s seas are now in crisis. We humans are polluting our waters and destroying precious habitats. We’re harming the species that live there and reducing the ocean’s ability to help fight the climate crisis.

According to the World Wildlife Fund some three billion people now depend on fish as part of their diet. As a result of human consumption and human pollution, in less than a century once-thriving marine ecosystems have become deserts, with many of the world’s best known fish (such as cod) facing extinction. Indeed, the total biomass of fish has fallen by an estimated 100 million tonnes since prehistoric times.

According to the United Nations 90% of the world’s fish stocks have already been used up.

What about sustainable fishing? In theory, sustainable fishing ensures that fisheries continue to thrive in marine and freshwater habitats. It is certainly true that people have fished sustainably for thousands of years. As ‘National Geographic’ reported, the Tagbanua people of the Philippines hunt for specific species at different times of the year, which maintains healthy stocks of different fish. They also use sustainable methods such as spears. But they are the exception to the rule. To make fishing genuinely sustainable would require us to stop fishing more or less completely for several years to allow stocks to build up and then to reduce catch sizes to a fraction of what they are today. Having said this, the move to offer sustainably sourced fish is to be encouraged and if we were to offer fish recipes this is the fish we were to offer.

A disconnect with nature

Sadly, most people think about fish as food and not as wildlife. This way of viewing fish creates a deep disconnect with nature. The world’s oceans and rivers are seen simply as a resource rather than as a vital part of a healthy ecosystem.

Which brings me to another shocking fact: more than 55 percent of ocean surface is covered by industrial fishing. That’s more than four times the area covered by agriculture. Those involved in fishing perceive fish as being ‘free’ and, of course, their activities are heavily subsidised. Governments spend an estimated US$35 billion worldwide every year to support the fishing sector, which averages to about 20% of the total value of all marine fish caught at sea and brought to port. This leads to overfishing and over-exploitation of fishery resources. To date, World Trade Organization (WTO) members have been unable to reach a deal to curb fishery subsidies.

Aquafarms, by the way, are far from being environmentally friendly. Every acre of farm produces about as much waste as a town of 10,000 people. It isn’t pleasant for the fish, either, which spend their whole lives (generally around 24 months) in cesspools filled with faeces, parasites, antibiotics, and pesticides. These toxic materials obviously spread to surrounding areas causing contamination and death.

The curse of industrialisation

Fishing has become increasingly mechanised. A typical floating fish factory can catch and process 1500 tonnes of fish a day. It achieves this by one of two main methods:

  • Bottom trawling, which is the practice of dragging an open fishing net along the ocean floor. While trawling nets target species such as cod, shrimp, and prawns, these moving death traps catch any animal that crosses their path. Bottom trawling damages also ocean floor ecosystems that animals rely on for survival. As an aside, bottom trawling unleashes the same amount of CO2 into the atmosphere as air travel. It also damages other habitats such as coral reefs.
  • Longline fishing, which is the practice of stretching nets with baited hooks across miles of ocean. The nets typically target tuna fish, but, like bottom trawlers, longlines indiscriminately capture and kill. Seabirds also suffer the consequences of longline fishing. As they dive beneath the surface for food, seabirds get caught in longline fishing hooks and drown.

One of the worst side effects of industrial fishing is called bycatch – fish that is caught but of no value. For example, a combination of bycatch and deliberate fishing kills 270 million sharks a year! To offer, it has also killed over 80% of the dolphins in the Indian Ocean. Industrial fishing harms ocean ecosystems long after the actual fishing is over. Old nets and other gear (aka ‘ghost gear’) left floating in the sea ensnares marine life and contaminates the oceans with plastic for decades. Fishing nets account for almost half of the contents of the Great Pacific Garbage Patch.

Fish welfare is another issue

It is estimated that industrial fishing kills 2.3 trillion wild fish a year. I am afraid it is not true that fish have low intelligence and don’t feel pain. Scientists have discovered that fish have complex inner lives, social dynamics and problem-solving skills. They care for and defend their babies. They seek comfort from one another when they are stressed. They recognise other fish and even different people. They have a nervous system that feels pain. In short, they are very similar to land-based animals. Fishing brings fish a great deal of suffering. It is killing off their natural environment. There are the dangers associated with ghost gear; the constant unhappiness of being trapped in a fish farm; and the misery of a long and protracted death trapped in nets or caught by a hook. Compare this to wild game birds who at least get to live a natural life followed by quick and painless deaths.

The good news

The UN, the EU, the WTO, other NGOs, governments and, of course, consumers are waking up to this issue. There is a real and determined push to make fishing much more sustainable. Until this develops further, however, Honey’s will not be adding fish to our menu.