🐠 Farmed fish CAN be healthy!? The underwater regenerative revolution

🌊 This newsletter is a DEEP DIVE into regenerative aquaculture, a topic I am increasingly PASSIONATE about for both planetary and human health. I hope you find this topic as inspiring, educational, and hopeful as I do!! Let’s dig in and LEARN!! 💗🪸 

The ocean covers more than 70% of the Earth's surface, produces approximately half of the world's oxygen, absorbs nearly a third of global carbon dioxide emissions, and is home to an incredibly complex web of life – housing over 80% of the Earth’s biodiversity. Yet, our marine ecosystems are under IMMENSE pressure and rapid destruction—from industrial over-fishing, devastating “bottom trawling” to capture huge amounts of sea-floor fish, plastic and chemical pollution, deep sea mining for rare metals, coastal destruction for development, sound and noise pollution from boats, and resultant mass biodiversity loss. It is estimated that a staggering 46% of the plastic waste in the Great Pacific Garbage Patch comes from discarded commercial fishing nets and gear alone, and overfishing has wiped out entire fish species, disrupting food chains and ecosystems worldwide. Ugh, it’s bad. 🤦‍♀️ 

But what if seafood production could actually heal the ocean instead of harming it, while also producing the highest quality, safest seafood for human consumption? This is regenerative aquaculture—a stunning approach to seafood production that enhances, rather than depletes, the oceans. When properly done, regenerative aquaculture blends traditional indigenous practices with advanced modern technology to steward the oceans rather than exploit them. This has been blowing my mind recently: I have been SO focused on regenerative agriculture the past several years I have totally missed the boat on REGENERATIVE AQUACULTURE… but not anymore… I’ve dived in and I’m hooked on this topic, as it has similar massive potential to support human health and planetary healing as land-based solutions. 

To help us understand this food system revolution, I asked ocean-expert James Arthur, founder of Seatopia, to chat with me and teach me all about regenerative aquaculture: watch our conversation on Youtube HERE, with a summary below. (We also made some epic sashimi recipes!).

James is a world leader on this topic – he has spent 10 years LIVING on a sailboat exploring the Pacific, visiting regenerative aquaculture farms all over the world, and is the first person to bring regeneratively raised seafood to market on a large scale.  

Part of his inspiration for this mission was sparked when he saw the devastating human impact on marine ecosystems, like trash littered across remote beaches of the Galapagos he sailed to. 😢 This was poignantly reminiscent of my own devastation seeing mountains of plastic along the beaches of the Osa Peninsula of Costa Rica last summer, one of the most remote rainforests on earth, which I wrote about back in July. 

✍️ Read more: Newsletter #21: The surprising links between plastic and metabolism, and 11 ways to protect yourself

Something is very wrong with our oceans, but there IS hope. READ ON! ♥️🌊 

🐟️ What is regenerative aquaculture?

I personally will not eat conventionally farmed fish on a menu or from the store, just like I massively avoid factory-farmed meats, dairy, and eggs. Conventionally farmed salmon always seems to look sickly pale and sad, and tastes fully bland. Conventionally farmed fish have been shown to contain polychlorinated biphenyls (PCBs), dioxins, antibiotics and pesticide residues, heavy metals like mercury and arsenic, microplastics, flame retardants, higher inflammatory omega-6 levels, and mycotoxins from grain-based feed. 🤮 Many of these problems are also common in wild fish, unfortunately.

But what I’m learning is that just like not all land-based farming is bad, not all farmed fish is bad either. It COMPLETELY depends on how it's done. One way can hurt the environment and health; one way can heal them. A fish raised through regenerative aquaculture is as different from a conventional farmed fish as a regeneratively-raised, pasture-fed cow is from a feedlot cow stuck in filthy, crowded conditions.

Conventionally versus regeneratively farmed fish are a different universe, and we need to know what these terms mean if we’re going to understand what’s going into our bodies and how our food choices are impacting Mother Earth. According to James: “Regenerative aquaculture is just mimicking natural ecosystems—learning how to raise seafood in symbiotic relationships with biodiverse species.” It’s very different from monoculture-based, industrial fish farming - where a single type of fish is raised in isolated, cramped conditions being fed a species-inappropriate diet (there’s no fish out there normally eating corn, wheat, and soy, right?).

Unlike conventional fish farms, which can become cesspools of waste and disease, these regenerative systems work in harmony with nature: “When you have a handful of species working in proximity, you can create these beautiful regenerative ecosystems. These can actually be high-density, if they are structured in a healthy way. Think about a rainforest or a coral reef: these are very high-density abundance through diversity. If you only have one species – like monocrop agriculture – any disruption can wipe it out. But in diverse, high-density environments, symbiotic relationships create resilience. So we’re learning to integrate different species to catalyze those ecosystem services each one provides. And as long as the feed at the top is clean, you’re actually creating beautiful new ecosystems.”

♻️ Regenerative aquaculture isn’t a single method—it’s a mindset rooted in ecology

Regenerative aquaculture is about designing food systems that work with nature, not against it. Depending on the environment, species, and goals, regenerative aquaculture can look like:

1. 🪸 Open-Ocean Polyculture (IMTA):

Imagine clean ocean currents flowing through a thoughtfully designed underwater farm, where multiple species are cultivated in layers—each playing a role in a regenerative ecosystem. This is Integrated Multi-Trophic Aquaculture (IMTA): a biomimetic approach to seafood production that transforms waste into nourishment.

At the center of the system, finfish like kanpachi or branzino swim in low-density pens, raised on clean, algae-based diets. As they grow, their nutrient-rich waste is released into the surrounding water—not as pollution, but as food for other species.

Surrounding the pens, kelp and seaweed are suspended on longlines and ropes, strategically placed to absorb dissolved nitrogen and CO₂. These fast-growing marine plants not only purify the water—they also sequester carbon and provide habitat for juvenile fish.

Nearby, shellfish like mussels, scallops, and oysters are suspended in lantern nets or on longlines—both up-current and down-current of the fish pens—where they filter phytoplankton and fine particulates, improving water clarity and quality.

On the seafloor below, deposit feeders like sea cucumbers, sea urchins, crabs, or lobsters consume the heavier organic matter that settles from above, closing the nutrient loop.

This isn't just a farm—it’s a vertically integrated, living reef. A multi-layered ecosystem where every organism has a role, and “waste” becomes resource.

At its best, this system is a living symphony—seaweed, shellfish, and finfish harmonizing in a regenerative dance, restoring ocean health while producing clean, nutrient-dense food. 🎻 

2. 🐚 Scallops in Hanging Lanterns

Suspended in mesh trays in pristine bays, scallops filter microscopic plankton directly from the water column—no feed, no antibiotics, no damage to the seafloor. In fact, they leave the water cleaner than they found it, acting as the ocean’s quiet custodians.

These farms require zero synthetic inputs and create structure in the water that builds biodiversity, attracting fish, crabs, and other marine life. Seatopia, for instance, works with scallop farms in Peru that are so clean and beautiful you can snorkel alongside the shellfish and watch schools of juvenile fish taking refuge in the hanging lantern structures!!

It’s a far cry from conventional bottom trawl-caught scallops, where massive dredges scrape the ocean floor—destroying seafloor habitats, stirring up carbon, and catching everything in their path. 🤦‍♀️ 

In contrast, regeneratively farmed scallops support ocean health, sequester carbon through their calcium carbonate shells, and contribute to local marine ecosystems—not deplete them.

3. 🌴 Mangrove-Integrated Aquaculture

Rather than clear mangroves, regenerative shrimp and finfish farms can enhance these vital coastal ecosystems. Mangroves stabilize shorelines, sequester carbon, and host hundreds of species. When designed correctly, aquaculture operations feed into mangrove resilience, with shrimp ponds functioning like intertidal wetlands.

In Thailand, Vietnam and Ecuador, models like “mangrove silvofishery” are incentivizing restoration of mangroves with integrated mangrove aquaculture.

4. 🔁 Land-Based Closed-Loop RAS + Biofilter Farms

Inland systems using Recirculating Aquaculture Systems (RAS) raise fish without ever polluting waterways. But the best regenerative systems go a step further: they turn fish excretions (i.e., poop!) into plant fertilizer—growing food, biofuel crops, or hemp with the nutrient-rich water. These are truly closed-loop ecosystems, mimicking nature’s waste-free logic.

Some of Seatopia’s partner farms even grow cannabis, duckweed, or watercress as part of their filtration matrix—functional plants doubling as habitat, medicine or food.

5. 🏞️ Extensive Estuary Aquaculture (Veta la Palma/Esteros Lubimar–style)

In places like southern Spain, aquaculture farms operate like floodplains, restoring wetlands while raising high-value species like sea bream, sea bass, mullet, and shrimp. These systems rely on natural trophic food chains—the fish eat plankton, shrimp, and other organisms growing in the water naturally. Stewardship of abundant microalgae canals support abundant high trophic, high value seafood.

Birds return, water quality improves, and the fish? Perfectly adapted, nutrient-dense, and wildly delicious.

Regenerative aquaculture is diverse by design.

Whether it’s scallops filtering seawater in Peru, sea bream thriving in rewilded extensive farm estuaries, or land-based trout nourished by microalgae and filtered by plants, each system aims to restore while producing. These aren’t just farms—they’re living ecosystems, often beautiful enough to dive into!

You know I LOVE visiting regenerative farms more than anything… see my favorite 11 in Newsletter #48: 🐄 The quickest path to healthy humans: love the soil! Maybe my next adventure is diving at regenerative aquaculture farms!! 😄🏊🤞

🤝 Parallels between regenerative agriculture and regenerative aquaculture

Many of us are familiar with the principles of regenerative agriculture—practices like rotational grazing, cover cropping, and composting that restore soil health and increase biodiversity. I’ve produced a ton of content about regenerative agriculture, which you can see here:

• ✍️ Read more: Newsletter articles

  • Newsletter #24: THE #1 thing we can do to improve health

  • Newsletter #48: 🐄 The quickest path to healthy humans: love the soil

• ✍️ Read more: Levels blog article 

  • “Why the way our food is grown matters for metabolic health”

• 🎥 Watch:

  • My interview with Molly Chester, founder of Apricot Lane Farms

  • My interview with Will Harris, owner of White Oak Pastures

Regenerative aquaculture operates on the same principles as regenerative agriculture:

• 🎣 Diversity over monoculture: Just as regenerative farms grow multiple crops nearby each other to support soil health (and echews monoculture), regenerative aquaculture integrates different species (such as fish, shellfish, and seaweed) to maintain ecological balance. When we think of unhealthy fish farming, we’re thinking about a single type of fish being raised in cramped, dirty conditions eating species inappropriate foods like corn and soy, similar to factory-farmed cows or endless rows of monoculture wheat. 

• 🙅‍♀️ No toxic inputs: Whereas conventional farming relies on chemical fertilizers and synthetic pesticides, industrial fish farming often uses antibiotics and grain-based, species-inappropriate feed. Regenerative aquaculture eliminates these inputs by using natural filtration systems, no preventative antibiotics, no hormones, and sustainable non-GMO species-appropriate feed sources.

• 🕊️ Restoration instead of extraction: While industrial agriculture depletes soil by exploiting soil with a single crop season-after-season, without replenishing nutrients with cover crops, crop rotation, and polyculture, industrial fishing depletes the ocean through overfishing, toxic synthetic inputs like antibiotics, and ocean-floor trawling (which reminds me of aggressive land-based tilling!). Regenerative models aim to rebuild what has been lost—whether it’s topsoil or marine habitats.

• 🔢 Data driven: Just as many leading regenerative farms like White Buffalo Land Trust and are using advanced research methods like field data, sensors, and remote sensing to measure improvements in soil biology, soil carbon sequestration, soil water retention, and reduced erosion with regenerative farming, so too regenerative aquaculture leaders like Seatopia test every batch of fish for heavy metals and plastics and publishes their data online. 

James puts the comparison between conventional agriculture and regenerative aquaculture simply:

“It's the same analogy as the difference between factory-farmed chickens and pasture-raised chickens. Or factory-farmed cattle versus regenerative cattle raised through rotational grazing. Integrated, multi-species aquaculture involves multiple species working symbiotically together - a sustainable, ecosystem-respecting approach. Factory-farmed aquaculture — the one people usually think of when they hear “farmed fish” — often involves high-density farming, cheap feeds with species inappropriate foods like corn and soy, and it’s sold to people who don’t ask questions. But there IS another model: high-quality farming where fish and shellfish are raised on diets that optimize for health, in complex, multi-species ecosystems that build biodiversity rather than deplete. This yields fish with robust immune systems and high nutrient density. That model is completely different.

🤯🤯🤯 And it probably comes at no surprise, many of the same players in the conventional agriculture space have built the large factory-farmed fish operations: "Many of the SAME investors behind industrial agriculture also own the largest aquaculture operations producing commodity seafood. It makes sense—they're feeding fish GMO corn, soy, and canola oil. And just like in humans, this leads to inflammation, weakened immune systems, and fatty liver disease in fish.

If consumers don’t ask what’s in the feed and just want cheap fish, that’s what they’ll get. Lacking their natural diet rich in omega-3s DHA and EPA, these fish are overloaded with omega-6s, which increases inflammation and disease risk—so they’re given preventive antibiotics.”

Cargill is an example of a destructive company that has its fingers in every aspect of our toxic food supply, including conventionally farmed fish. Cargill is one of the largest slaughterers of beef in the United States, supplies the eggs to McDonalds, brags about trying to get 100% of farmers in low-income countries to adopt toxic synthetic pesticides in partnership with ChemChina (they call it “crop protection” 🤢), produces mass quantities of high fructose corn syrup, soybean oil, and dozens of other chemical food additives, and are mass producers of soy, corn, and wheat based feeds for aquaculture. Of note, Cargill is the largest privately owned company in the US and their family has 21 current billionaires - more than any other family in the world - profiting off government subsidies, addicted consumers, and planetary destruction.

💙 An example of a healed ecosystem through regenerative aquaculture

A gorgeous example of successful regenerative aquaculture is Estero Azul, a farm in Cádiz, Spain, that evolved from the rehabilitated estuary of Veta La Palma which had been drained for a cattle farm. By restoring natural water flow and encouraging the growth of microalgae, the ecosystem came alive—supporting shrimp rich in DHA and EPA, which in turn nourished branzino, sea bream, and a vibrant web of wildlife, from mullet to flamingos. What was once barren is now a biodiverse haven, proving that when farmers prioritize ecosystem health, abundance follows for both nature and people.

James says: “Now you have this system that is flowing very efficiently, creating this abundantly healthy ecosystem that also has this huge biodiversity of flamingos and osprey and mullet and this myriad of other species— and all of these species are existing here today because the farmers said, ‘How do we optimize the environment to create abundance that would not only be able to feed us and we could export and feed the world, but that also creates a healthy environment for all the birds and all the wildlife?’ Some people might say, ‘Oh, you’re wasting so much fish allowing these birds to come and prey.’  But if you approach it from regenerative principles, you know that where there’s lots of life, there’s lots of death. And you need predators to help cull and clean, and the sign of predators is a sign of an ecosystem. When we go diving and we don’t see sharks, that means there’s not enough of a healthy environment. When you see sharks, it’s a sign that there’s an abundance of life as well.”

🌊 Restoring ocean health through regenerative aquaculture

Just as regenerative agriculture restores biodiversity and fertility to depleted soils, regenerative aquaculture can breathe life into nutrient-poor ocean deserts, known as oligotrophic zones. These are areas where waters are so low in nutrients that kelp, shellfish, and most marine life struggle to grow.

But when low-density, well-managed open-ocean fish farms are introduced into these areas—with fish fed clean, omega-3-rich diets like algae and insect protein—their nutrient-rich waste (poop) begins to reseed the ecosystem.

This gentle nutrient enrichment can:

• 🌿 Fuel kelp growth, especially fast-growing species like giant kelp (which can grow up to 2 feet per day),

• 🐚 Support filter-feeders like mussels and scallops, who naturally clean the water, and;

• 🪸 Create habitats that attract wild fish, functioning like living Fish Aggregating Devices (FADs).

In essence, a carefully designed regenerative aquaculture site can transform a barren ocean desert into a vibrant, biodiverse, carbon-sequestering oasis.

Kelp becomes not just a crop, but blue natural infrastructure—absorbing CO₂, sheltering marine life, and restoring ecological balance in places where little life once thrived.

🌎️ The ocean’s critical role in carbon cycles and healing the global environment

As alluded to above, one of the most fascinating aspects of regenerative aquaculture is its potential to sequester massive amounts of carbon from the atmosphere. (I always laugh when I hear of “innovation” in carbon sequestration technology… I’m like… hello… trees and regenerative root systems do that for FREE! 🙄 And now I know… phytoplankton and marine life does this on a massive scale, as well!  So perhaps if we didn’t destroy forests, our soil, and the oceans with irresponsible industrial practices and pollution, we wouldn't need to spend so many billions of taxpayer dollars on “innovation” for something nature ALREADY DOES! 🙄🙄🙄 Humans: why are we being so dumb?)

“You have species like blue whales that eat enormous quantities of carbon (like swarms of zooplankton, to schools of fish, to small mammals) at the surface and then dive and poop and store it down in the deep. There is data that shows just phytoplankton and zooplankton moving up to the surface to photosynthesize and then sinking down into the nutrient-rich waters at night is moving immense amounts of carbon. The ecosystem services and the ability to catalyze those sorts of carbon cycles has far more potential in the ocean than it does on land.” Additionally, as scallops grow, they build their shells from calcium carbonate, sequestering carbon in the process—roughly 11.5 pounds of shell can lock away 1 pound of carbon, storing it long-term in a stable mineral form.

Kelp, for example, can grow up to two feet per day, absorbing CO2 faster than land-based forests. By cultivating seaweed alongside fish and shellfish, regenerative aquaculture can enhance the ocean’s ability to sequester carbon while providing sustainable food sources.

🤔 Why this matters for human health

We are what we eat—and right now, eating fish comes with real risks. Government agencies advise pregnant women to limit themselves to just ONE serving per week from the “good choices” list of fish. The primary concern is mercury, a neurotoxin that accumulates in fish due to industrial pollution. Major sources of mercury include coal-fired power plants and metal mining—this is not a natural occurrence, but the result of human activity. It's a frustrating reality: fish are among the most concentrated sources of bioavailable omega-3 fatty acids, critical for brain development and cellular health. Yet we’re forced to limit them because of preventable contamination. This is a public health and regulatory failure, and yet the onus for protecting ourselves and our children comes down to personal responsibility. 

So now that we know a bit more about the issues with fish, let’s look at our buying options: 

• 🪸 Wild caught fish: Unfortunately, larger wild caught fish can bioaccumulate toxins, plastics, and heavy metals from the smaller fish they eat, leading to a suboptimal product. Because larger fish eat lots and lots of smaller fish throughout their life, they can accumulate high levels of toxins. And even smaller fish can be contaminated if the river, lake, or other body of water they are fished from is locally contaminated. 

• 🎣 Conventionally farmed fish: These fish are often fed species-inappropriate diets and farmed fish have been found to contain many toxins, as mentioned at the beginning of this essay—all of which can disrupt hormones, impair immunity, and increase long-term health risks in both the fish and the human.

• 🌊 Regeneratively aquaculture raised fish: Well-raised regenerative fish are fed clean, species-appropriate diets rich in microalgae—an abundant source of omega-3s like EPA and DHA—paired with innovative proteins like insects and mycelium that reflect natural feeding behaviors (don’t get freaked out by insect protein— many fish already eat insects, think flyfishing 🎣 ). Raised in controlled environments, these fish can be routinely tested for toxins like mercury and microplastics, then flash-frozen at ultra-low temperatures to ensure safety from parasites.

Many of us eat fish because we know it’s a great source of omega-3 fatty acids, incredible for brain function, heart health, and reducing inflammation. But now, choosing the right, “safe” fish feels like a landmine with no great options except maybe super tiny fish like sardines (which no one wants to eat a giant amount of, and which come in cans, which isn’t great either! 🤦‍♀️ ). 

Regenerative aquaculture provides a controlled environment where fish can thrive with much less exposure to these contaminants from their diet. The result is seafood that is not only rich in beneficial nutrients but also free from harmful substances. Ever since starting my twice yearly testing with Function Health, I’ve been able to track my omega-3 and omega-6 levels, my mercury levels, and even my PFAS and BPA levels. Now that I’m eating a lot more Seatopia fish, I can’t wait to check my levels over time to see how they change. 

“Unlike the increasingly toxic ocean environments caused by the continued dumping of pollutants into rivers, streams, and seas, clean aquaculture systems with clean feed produce predictably clean fish. When feed is optimized for higher omega-3 content, the fish reflect that. And when the feed comes from lower on the food chain—naturally lower in mercury and microplastics—the resulting fish contain significantly less of those contaminants.” 

I hope you enjoyed this overview of this fascinating art and science of regenerative aquaculture, and feel more empowered to be a more conscious consumer of seafood and ocean stewardship!

💗 , Dr. Casey

🐟️ Seatopia has graciously offered 15% off your purchase of $100 or more. This fish is the most flavorful and fresh tasting fish I’ve ever eaten - hands down - and ships to you frozen on dry ice for prices similar to what you’d find in a regular store. You also get a free eBook with use of my link that includes my very own pesto recipe alongside a few others, featuring Seatopia’s seabream, steelhead, and scallops.

I cannot recommend it highly enough - I have been eating it every single day. You can build your own box or get a curated box.  The Fish & Shellfish Variety Box is a great place to start for first timers! If you build your own box, my favorites are the scallops (which I eat raw!), the cold smoked steelhead (like the best lox you’ve ever had), the Caleta bay steelhead loin (which my husband said was the best fish he’s ever eaten), and the Sea Bream (which I made as sashimi with James with a homemade multi-herb pesto!).

👀 In Case You Missed It

New study alert! 🚨“A Pilot Study of a Ketogenic Diet in Bipolar Disorder: Clinical, Metabolic and Magnetic Resonance Spectroscopy Findings”

BJPsych Open just published a new bipolar treatment pilot study that describes the principle results of the first ever European trial of ketogenic diet for serious mental illness. This is the first published study to use advanced neuroimaging to interrogate metabolic changes in the brain with a ketogenic intervention in bipolar disorder, and represents an incredible achievement, and suggests that the effects of a ketogenic diet may extend beyond epilepsy.

Taken together with the 2022 retrospective analysis in France from Dr. Danan and Dr. Georgia Ede and Dr. Shebani Sethi’s pilot study at Stanford, published last year, these trial results offer hope for a new treatment option to the millions worldwide who struggle with bipolar disorder. This paper also offers new directions for the worldwide community of physicians and scientists dedicated to treating and studying bipolar spectrum disorders.

Read the full study here and the twitter thread about this here.

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