The Many Faces of Aquaculture: An Introduction to Fish Farming

Is there a sight more idyllic, peaceful, and touching than that of a fish farmer tending to his flock? In case you aren’t aware of how fish farming works, here’s a sample day in the life of a fish farmer:

Just before dawn each day, he rises from his water bed, dons his denim board shorts, enjoys a mugful of the fermented fish liver brew he keeps stewing in a bucket beside the front door, leaves his rickety old farmhouse boat, and sets out for a day’s labor. Wherever his paddleboat passes, carp, salmon, tilapia, phytoplankton, algae, and shrimp cease predating each other and crest to greet him. The fish farmer knows each by name and has a wink, chin scratch, and fish flake for every little shy fry cowering behind its mother. At slaughtering time, the old farmer sheds a single, solitary tear – every single time, whether it’s the ornery old catfish with greying whiskers or the months-old tiger prawn just hitting his prime (which, unfortunately for the prawn, is when flavor and texture are at their peak). It’s a simple life, but, all-in-all, an honorable one steeped in tradition, stewardship, and respect for the natural flow of aquatic life.

Okay, okay… how does fish farming really work? Well, it encompasses more than just fish, for one. A more accurate term to use is actually aquaculture, which includes multiple varieties of fish farms, shrimp (and other crustacean) farms, shellfish (oyster, clam, mussel, abalone, etc) farms, and sea ranches (this is the coolest). Let’s dig in.

Humans have been engaging in aquaculture since antiquity, and perhaps even earlier. An Australian archaeologist, Dr. Heather Builth, has gathered evidence that the aboriginal Gunditjmara of Western Victoria built and oversaw massive eel farms, as early as 6000 BC, that sustained villages and even an industry of smoked eel products. The ancient Chinese started farming carp over 4,000 years ago and wrote the definitive book on the subject somewhere around 500 BC. During the Tang Dynasty, the Chinese discovered that certain species of freshwater carp complemented each other in the same pond, boosting productivity, saving space, and birthing polyculture fish farming. In addition to China, fish farming spread into the Indian subcontinent, ancient Egypt, the Greco-Roman world, medieval Europe, Hawaii (pre-colonial), and just about everywhere else.

Nowadays, about half of all fish eaten worldwide comes from aquaculture. To a bunch of health-conscious wild salmon eaters like you folks, that probably sounds like a nutritive disaster. After all, everyone knows that wild trumps farmed, every single time. Right? Well, not exactly, but I won’t get into that right now. Check back tomorrow. This time, I’m going to briefly discuss the various types of aquaculture.

Extensive Fish Farms

Extensive fish farming utilizes natural photosynthetic production of food (algae, plankton, mollusks, crustaceans) to feed the fish. This type of farming isn’t the most productive, but it requires little labor, low overhead, and very little input from the farmer. You just need water, some fish, and a way to pen them in. Things can obviously get more elaborate, but those are the bare minimum. Most tilapia and carp are farmed using extensive methods.

Extensive farming is obviously the most sustainable and does the least environmental damage, but it isn’t always economically viable and it doesn’t work for every species. Carnivorous fish (which is most of ’em) need to eat fish, or pellets made from fish. Salmon, for example, eat the fish that eat the plankton; they don’t eat the plankton directly. On the other hand, tilapia, which feed directly on phytoplankton, and carp, which eat benthic animals (bottom feeder), are great for this type of farming because they don’t require food pellets or other, smaller fish for food.

Intensive Fish Farms

Intensive fish farming uses an external food supply – pellets, fishmeal, corn, soy, even “feathermeal” – to feed the carnivorous fish. The population density is high, antibiotic usage is high, food waste is high, and sewage output is high in intensive fish farming. Water quality is paramount and usually requires a robust water purification system, if the farm is a closed system, like a pond, ditch, or tank. If the farm uses cages in rivers or the open sea, water purification obviously isn’t as necessary.

Either way, intensive fish farming requires constant maintenance and vigilance. If management is poor or funding inadequate, things can get pretty bad: toxic runoff, antibiotic-resistant bacteria, introduction of farmed, perhaps diseased species into wild populations, excess food and waste influencing wild population densities, stressed out fish. Heck, even if management is on top of their game, antibiotics are still a necessity, food is being wasted and eaten by wild sea life, which throws off local wild population densities, and the fish are living in cramped conditions which increases stress. It can be done well, and I’ll get into that next time, but it is difficult to do, and most aren’t doing it.

Shrimp Farms

Traditional shrimp farming took place in brackish water ponds or mangrove swamps, the shrimp’s natural habitats, and often involved other complementary species, like rice or fish. This was subsistence farming, suitable for a family or even an entire village, but not for an industry. Today, shrimp farming displaces mangrove swamps and other coastal systems across China, Thailand, India, and Vietnam, among other countries. There are three primary types of coastal shrimp farms: extensive, semi-intensive, and intensive shrimp farms. Extensive shrimp farming uses low densities, about two or three animals for every square meter of water, and generally do not need to supplement feed supplies. They’re on the coast, so the tide’s enough to keep the water fresh, and extensive farmers often use wild stock. Semi-intensive shrimp farming ups the density to about 10-30 shrimp per square meter, increasing the requirement for food. In semi-intensive farms, shrimp get supplemental shrimp feed, and artificial algae blooms take care of the rest. In intensive shrimp farms, the shrimp populations reach even greater densities and rely almost entirely on supplemental shrimp feed.

Infectious disease is a frequent concern in shrimp farming. It kills profits, sure, but it also infects and kills wild shrimp living near or around the coastal farms. Most shrimp diseases are viral, without any real treatment save for prevention, but preventing viral disease from spreading among shrimp in super-dense living conditions isn’t easy. And then there’s bacterial disease. Most shrimp farms use antibiotics to cull bacterial diseases; one study found that 74% of Thai shrimp farmers surveyed used antibiotics in their operations. As the shrimp population increases in density, larger amounts of antibiotics are required. This leads to resistant bacteria, which is fairly common in both Vietnamese and Brazilian shrimp farms (and, I’d imagine, shrimp farms in general), and, again, spreads to affect wild populations.

Shellfish Aquaculture

Shellfish farming is actually quite impressive. There’s very little active farming required, and, since bivalves tend to be sedentary creatures, farmers don’t worry about their clams escaping to deep water or their mussels fomenting for freedom. Since bivalves are filter-feeders – water passes through their filters, leaving behind algae and other tasty microorganisms – they also require no direct food from the farmers. The filtering also serves as a water purification system. Raised in the same farm as pooping, food-wasting fish, bivalves work especially well, eating the leftovers, cleaning the water of fish waste, and getting big and delicious in the process. All in all, farmed shellfish – scallops, clams, oysters, mussels, and abalone are the big ones – are more sustainable than wild caught shellfish, and live quite similar lives, too.

Integrated Agriculture-Aquaculture

The world is a massive system with millions of variables, each one interrelated to the next, working (or not) to make sure things flow smoothly. Obviously, we lowly hominids can’t recreate the near infinite complexity of the entirety of nature, but we can make decent attempts at small portions. Asian rice farmers have been raising carp in their rice paddies for hundreds of years with great success. The carp eat the plankton, preventing the latter from outcompeting the rice for nutrients, comb the bottom soil, which releases more nutrients, and produce a steady source of fertilizer for the rice. There are plenty of other possible aquacultural-agricultural integration permutations used across the world, like rice/shrimp, fish/grass, fish/duck, fish/pig, fish/chicken, but the fish you come across in the big supermarket probably didn’t have a pig, duck, or rice plant for a friend.

While integrated aquaculture, in many cases, is more cost-effective than either monoculture by itself, the initial production costs and knowledge required is a large barrier for widespread adoption. That is, you can’t implement sustainable integrated agriculture-aquaculture systems on a large scale without knowhow, planning, and money. Recreating natural symbioses (even on a small scale) isn’t simple.

Integrated Multi-Trophic Aquaculture (IMTA)

IMTA is very similar to integrated agriculture-aquaculture systems in that they create mini ecosystems, only IMTA is limited purely to aquatic species. So, instead of rice-fish farms, you’ve got fish-seaweed-bivalve ecosystems-within-a-farm. Very cool. Perhaps the coolest example of IMTA on a large scale is Veta la Palma, a Spanish farm built on a former cattle feedlot that actually improves upon nature. It produces tons of shrimp, bass, bream, and mullet each year. Each fish pond is lined with native plants that maintain nutrient balances in the water. Each fish forages for its own food in water that’s constantly replenished by the tides. Over 250 species of birds (up from 50 before the farm was built) attend to feed on the farmed fish, a practice encouraged by the farmers because it means “the whole system is working.” And, most importantly, they produce fantastic seafood.

Fish Ranching

They may not have big floppy ears that perk up, but fish can hear; they may not have big brains, but they can learn. Fish ranchers capitalize on both attributes by playing a specific sound every time the fish are fed. Eventually, the fish associate the sound with food and, after plenty of conditioning, will come to the sound every time they hear it. So, rather than keeping the fish in crowded cages, nets, or ponds and feeding them weird pellets, ranchers let their fish range freely in open water, feeding on regular fish fare. When it’s time to harvest, the sound will draw them back. Different species have different recall rates, though; in one ranching test using tilapia and carp in a large reservoir, only 13% of the original tilapia heeded the call, while over 2/3 of the carp came back. But with the original crew came hangers-on – other carp, tilapia, and a few other fish species from the reservoir – and the ranchers’ final haul was over twice as big as the original group of fish. Another type of ranching uses fish with a homing instinct, like the Nepalese mahseer (a type of carp). The mahseer hatches upriver and is fed for about a year, until it grows large enough to be released into the river. It spends a good two or three years in the wild eating (on mother nature’s dime!), growing, and working its way back to the original spawning grounds. The fully grown mahseer always returns to the place of birth, making harvesting a simple task.

Ranching definitely has its benefits. The fish get a more natural diet (although they start on pellets), which the ranchers don’t have to pay for and that doesn’t dose the surrounding environs with excessive nutrients; the fish aren’t crowded into unnatural habitats, lowering both the incidence of disease and parasites and the necessity of antibiotic administration; there are fewer packed crowds of pooping, scaly sewage production facilities to worry about.

As you can see, aquaculture has many faces, some homelier than others. It’s impossible to keep track of all the different types, because everybody does it differently and every species requires its own setup. They are simply too numerous and diverse. Tomorrow, however, I’ll dig through the muck and explain which aquaculture products are worth eating based on nutrition and environmental concerns, because, let’s face it – that’s what it really comes down to, right?

Thanks for reading. Share your thoughts in the comment board and Grok on!

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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43 thoughts on “The Many Faces of Aquaculture: An Introduction to Fish Farming”

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  1. Good post. Just so happened I was reading about aquaculture yesterday (and I am constantly lamenting the destruction of our oceans from overfishing), so this was fresh on my mind.

  2. Good warmup post, looking forward to tomorrow’s! I love natural seafood but just like grass fed beef, really can’t afford to eat that much of it. Hopefully the primal world can help divert funds used for corn subsidization and the like towards actual food in the future!

  3. Your idyllic peaceful fish farmer sounds like the old man in the sea. That book always struck me with the reference to the poor old man who couldn’t afford much food but, thankfully, had access to the huge barrel of fermented fish oil. That’s tradition!

    This was an informative post. Thanks for taking the time to research all that. Now I just need to know where I can get some IMTA or ranched fish. Hopefully that will show up in the blog post tomorrow! 🙂

    1. Really interesting! Something I’ve been wondering about for some time. Looking forward to tomorrow’s post.

  4. This is a pretty interesting topic for me–I’m interested in aquaponics, which is intensive closed-system fish culture in symbiosis with food plants. Complete Primal nutrition in a tank! The cool thing about it is that since it’s a closed system with live animals you are constrained from using chemical fertilizers and such, since they would kill the fish.

    You have to feed the fish, which is the weakness of the technology, but I’m working on figuring out how to grow enough duckweed and other aquatic plants to take care of their feding needs with no industrial inputs, only private/neighorbood compost or possibly vegetable waste streams from local groceries or restaurants. Unfortunately I have no job at the moment, and therefore no money to spend freely, so I have four 55-gallon barrels (food-grade, recycled from a soda bottling plant) sitting in my yard and no pumps, pipes, plants or fish to put in them. I’ll get there someday.

    1. Yes, aquaponics is a very interesting topic for me as well. I’ve been watching it for years, and it seems like it’s starting to hit some critical mass for small-scale / home-scale setups. The Aussies have been doing a lot on this for a while, but now here in NA there is a lot of activity too.
      A couple hundred gallons of fish tank and some hydroponic-style beds can yield very significant harvest.
      It should be noted though that this is largely a great way to grow plants, with a few fish as a bonus – household-scale systems aren’t going to get you a fish per day or anything along those lines.

      1. Oh yeah, definitely aware that you get a lot more vegetables than fish out of the deal. But the fish are a nice bonus. 🙂

        Plus you can always expand if you get good at it, and then you’ll get more fish.

        1. I too have been thinking about this, but wondering if it would be possible to supplement the fish diet with insects/worms (fed a mix of local grasses or some other natural feed such as compost). Maybe that way I could get a greater yield of fish while still using nutritious inputs. As it is right now my home aquarium’s waste water is doing an amazing job at fertilizing this year’s garden seedlings.

  5. This may sound rather idiotic, but, is it possible to farm salt water species (ie oysters) in an inland pond? Could the water be made salty enough with provided aireation (? spelling) to sustain oysters for private usage? Not to sell, just for our own personal usage?

    1. I know that indoor salt water fish tanks take a lot of work and constant salt level monitoring. I think an inland pond would be equally time consuming and have high initial investment. I could be wrong though and it is an interesting idea.

    2. When farming with salt water, it is called mariculture. I believe it would be possible to make it salty enough for oysters, the hard part is getting the mix of salt right for the particular species.

      I have been looking into this myself recently (fish not oysters) and found that if you are going to make a pond, you will need to ensure that the fresh water is constantly topped up so that as the pond water evaporates, the remaining water in the pond does not become too concentrated with salt.

      On the other hand, you also need to make sure that the concentration doesn’t become too weak when it rains.

    3. I’d think maintaining salinity in the face of rain might be an issue, not to mention providing enough planktonic food to keep the oysters happy. When you have new water sloshing in from a neighboring ocean, both issues are solved…

  6. Hmmm… really makes me wonder if it would be possible to pop some carp in the backyard.

  7. Ranching is used in the Alaskan salmon fishery, too. Hatchery fry are released in a bay with no freshwater inlet. They go off and do their thing for 2-4 years (species-dependent) then when it’s time to spawn they head back to their bay. Of course, there’s no stream to swim up, and few if any true wild salmon, so the seiners swoop in, scoop them all up, and sell them. Virtually guaranteed catch of some sort (depending on ocean conditions in the intervening years) with no by-catch, little impact on wild stocks, and few overhead costs.

  8. I should say I found the post interesting, I eat a lot of seafood and look forward to more of this.
    Where I live (Sweden) it is quite easy to buy wild seafood, cod, shrimps, eal etc. But we also have the norwegian farmed salmon, which I’m not so sure is ok.

  9. I have been waiting for a post on this subject for a while. I remember reading a page on Food Renegade saying that some farmed raised fish is better than wild. It just depends on how the farmed raised fish is raised and what type of fish it is.

    You made it sound like it all farmed sellfish (scallops, clams, oysters, mussels) are better than wild.

    Does this mean I am safe to eat these things from any restaurant? Or at least say 80% of the time? I love scallops and wish to try other shellfish.

    I am really looking forward to tomorrows post!!

    1. Speaking as a random passerby who has noticed a trend, I find it a little creepy myself that you eagerly lie in wait for Toad’s posts so you can say basically the same thing over and over again.

    2. Look Geoff, I have never posted and mostly just lurk, but honestly you sound more like the loser living in his mom’s basement. At least Toad comments on someone’s (Mark’s) posts that are interesting and invite discussion. Not a single one of your comments has added anything to any discussion on this site where Toad at least blogs and makes an effort to stay informed in the paleo community. All I am saying is that if I was toad and you talked to me like that in real life (stalking me, belittling everything I say as a point) I would absolutely punch you in the mouth. Go make some bacon and quit trolling.

      1. Ridiculously obvious sock-puppeteer is ridiculously obvious. Go away, troll.

    3. Geoff and Emily,
      Please remember that Karma is real, Don’t ruin yours

      1. Really…. says who? You? Are you God? Do you speak final truth? I don’t want to condone beating up on a helpless little man like Toad but nevertheless Kharma is a pretty weak threat. If nothing else, if Kharma is real doesn’t that mean that Toad deserves to be made fun of because of something he did in a previous life right? Seriously who dies and comes back a Toad?

  10. the bit about the carp in the rice paddy sounds like companion planting. I’ve been researching that for my garden this year so it’s fresh on my mind. (the companion planting not the carp thing, I don’t have a rice paddy) 🙂

  11. Your intro was freaking hilarious.

    “…and has a wink, chin scratch, and fish flake for every little shy fry cowering behind its mother.”


  12. Looking forward to the next post with advice on what to choose. I have to say, I think farmed shrimp from Asia tastes a lot better than any wildcaught varieties, so I’m hoping that’s on the “yes” list!

  13. It’s nice you touch upon the notion that farming methods must be economically viable. In a previous post about non-aquatic farming you touched how upon how you wanted a farm to be as vertically integrated as possible which I frankly think is not economically viable for many farmers. We would think it silly to demand of Mark Sisson as a publisher of books to also grow the trees upon which pulp is ultimately made to print the books. Why should we demand such a high level of vertical integration for other industries? We should not.

  14. Nice write up on aquaculture.
    I work at a recirculating shrimp farm 25 miles from the ocean, raising Florida native species shrimp in salt water. Recirculating Aquaculture systems (RAS) is the most expensive way to farm, but it has the least impact on our environment. One thing that you missed about shrimp farming is that in the USA we are very regulated and we are not allowed to release, sell or eat any shrimp that are treated with antibiotics. We strive everyday to maintain an enviromentally friendly business and prodce a high quality product. We have invested in many thousands of dollars in solar energy, and research for energy efficiency in our systems. Fish farming is thousands of years old, and it is necessary to maintain seafood for consumption in the future. Thank you for taking the time to research and write an honest and factual blog about aquaculture.

  15. One of my most distinct memories from early childhood is of a tour through a fish farm/hatchery. Especially the part where they put all the eggs in a 5 gallon bucket and then squeeze the sperm out of the male fish into and stir it around with their hands.

    Such a beautiful natural process…

  16. Don’t get to freaked out over the information. take the time to research all of the info. There are a lot of valid points, but the author left out the other side of things. Like on the recirc systems where the bio-filters do remove everything bad from the water, and any system worth its while since around 2012 are not energy hogs. When you think about the fact that fish/shrimp are pretty much eating anything in the ocean the fact that they are really eating a 90-95% grain based feed (In the U.S….. Find your fish/shrimp, etc… farmed in the U.S. or inland other than Asia) they are actually living in a cleaner environment, less pollutants than the ocean, a more healthy diet, less pollutants……

    In short, don’t apply what is happening overseas to what is happening in Recirculating Farms here in the states. Like everything, you will find a bad apple in all, just like you can find a bad apple in an organic or any other type of farm. That doesn’t mean they are all bad.

    Aquaculture is a very expensive deal if it is going to be done right. Go with aquaponics if you want to do fish/shrimp and vegies. It can be done great in a backyard setting and you can get about any vegie you want as well as several types of fish. Cheaper to experiment with as well.

    Best of luck to all of you.

  17. Please check out the next wave of food (fish/plant) Aquaponics. Cleaner than lots of organic operations, uses waste to produce vegetables in abundance.Water is reused in a closed system making water deprived areas viable fish/vegetable producers.

    1. this was alright i guess a bit boring and droopy i could have learnt this off a kids show i really didn’t enjoy it

  18. actually when i think about it. it was absolutely terrible

  19. Interesting blog about fish types and their keeping. For their survival, it’s necessary to make the pond leak free with Pondpro2000 it is nontoxic and not harmful to fish.