In the world I'm making, humans trade with a variety of species, one of which is a society of merpeople. Humans typically acquire goods and services in the form of fish, pearls, under sea flora for medicine, navigation assistance, and passage through merfolk waters. What I would like to know is what would a race of merpeople likely want in exchange for goods and services?

Potentially Key Details:

  • Humans have the highest form of technology at something between late medieval and mid age of exploration depending on region where the merfolk are early to mid medieval generally speaking.

  • Metal work is limited for the merfolk (unless someone can tell me how metal work would function underwater but that may be a question for another time).

  • The merfolk live in large underwater cities often built from manipulated coral or other such underwater structures.

  • They farm fish by raising generations within underwater cages like modern pisciculture.

  • The common trade good in this world is gold coins but, generally speaking, most would still deal in bartering.

Physically the merpeople are in appearance human above the torso with their lower half being like a fish (Disney's little mermaid style) with the inclusion of gills on their neck and more fishlike eyes. They eat about as much as the average person would and can digest the same types of food as a fish would as well.

Merfolk society is not one united kingdom; there are many kingdoms under the sea that have their own established borders and trade routes among each other that may interact with human traders in different ways.

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    $\begingroup$ Can the merfolk live in an air environment? Are they familiar with/can they use fire? If not, it looks like you've almost answered your own question: metalwork. (And perhaps ceramics/pottery - anything that requires the use of fire for production) $\endgroup$ – Qami Aug 27 '19 at 16:35
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    $\begingroup$ Also, in case it's relevant/useful for other answers: how do your merfolk deal with fresh water? Can they/do they travel up rivers? $\endgroup$ – Qami Aug 27 '19 at 16:39
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    $\begingroup$ Just so I can clarify: is magic a thing in this world? Like, could you enchant objects and sell them? $\endgroup$ – cyber101 Aug 27 '19 at 16:44
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    $\begingroup$ @Cyn thanks for the makeover! much more palatable $\endgroup$ – John V. Aug 27 '19 at 18:09
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    $\begingroup$ So there are certain species of fish (Gorami) that have what is called a "labyrinth gill" which can trap water inside the folds of protective skin and survive for a period of time outside of the water. Most of these species live in areas where a stream might be prone to drying and flooding periodically. $\endgroup$ – hszmv Aug 27 '19 at 18:11

13 Answers 13


Let me list a few ideas:

  1. Metal products. It is very unlikely that there would be many merfolk willing to spend prolonged periods of time outside of water just to craft metal objects. Metal products can be many, from weapons(most likely harpoons, or other weapons that are meant to stab) to tools, jewelry and ornaments. While rare, you don't need to use much of metal for many tools, the main parts of tool might be from something else. For jewelry, metal being rare only increases their value.

  2. Ceramics(porcelain, pottery, etc.). For the same reason, it's unlikely that pottery would be mass produced by merfolk. Still it is decent way to store things. This might include some "chemical weapons" sealed in pottery. For example quicklime could be used in underwater warfare. When pot full of quicklime is thrown at someone, breaks and quicklime escapes into water, prepare for some burns.

  3. Boats. It might seem counterintuitive, but boats can still likely be of use to Merfolk. They're a very simple way of transporting a very large amount of comodities of any kind. These boats would be however have to be crafted with merfolks in mind, using tamed fish or whales to pull them.

  4. Building materials could still be of some use to them. However I am not sure what would be ideal for merfolk civilization.


  1. Nets! How could I have forgotten about nets. I'm pretty sure nets would be of use for merfolk. They don't need to be used just for fishing, they'd make - decent windows. While merfolk can probably make something similar out of underwater plants, it could still have use, or it could at least be treated as an exotic commodity (land-folk made means exotic).
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    $\begingroup$ Honestly, merfolk probably could have real windows not just net windows: close them to keep the plankton out, then open them because the water was getting stale. $\endgroup$ – Aaron Harun Aug 28 '19 at 13:02
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    $\begingroup$ Merfolk could even tow boats themselves (think of a cargo tricycle or wheelbarrow -- a human can power a decent amount of cargo, presumably a mer-person can as well.) $\endgroup$ – arp Aug 28 '19 at 15:34
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    $\begingroup$ Hydraulic concrete. $\endgroup$ – Joshua Aug 28 '19 at 16:26
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    $\begingroup$ Thinking about this, their boats wouldn't have to be 100% buoyant either. In fact, it might be useful if their buoyancy was adjusted to have them "float" at a certain depth (or better yet, was somehow adjustable) $\endgroup$ – T.E.D. Aug 29 '19 at 13:58
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    $\begingroup$ @TedPwyll Nothing is forever. Metal tools are much superior to anything made out of corral, rusting just means there will be constant demand for replacements. $\endgroup$ – ventsyv Aug 29 '19 at 19:04

Many of the ideas I had (metal goods, ceramics, etc) are well-described by other answers. So I'll focus on the ones that are not yet listed.


Even on land, secure storage of goods is an important service. Banks can secure actual goods (think safe deposit boxes) or virtual ones (a tally of your money, so you don't have to hide it under your mattress). And there are many non-banks that can keep goods safe. Safety here means both safe from others stealing it and safe from the environment.

Accumulating Wealth

Merfolk may also wish to own things that are not stored away but, rather, kept in production. For example, a flock of sheep. Milk, meat, and wool might be of direct use to a merperson, or they could be used to trade for other things or simply to accumulate wealth. Owning a flock and hiring humans to caretake it might work out better economically than simply trading for the actual goods you want each time you want them.

Depending on the laws of the human society, it is possible that a merperson who owned land (even if they could not live on it, or even visit) might have rights that they would not have otherwise. Voting (if it is a society that votes), or the occasional ear of the monarch, or other legal niceties accorded to landowners.

The goods the merfolk produce could pay for these things and their upkeep, and pay the humans they hire to look after them.

Record Keeping

Another poster mentioned writing and I agree it's a strong choice. Recording the history and stories of the merfolk, as well keeping records of their financial transactions would be very useful.

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    $\begingroup$ I really like this concept as a whole: having something like an interspecies bank or stock exchange managed by humans for the sack of logging/storing riches as well as history sounds like a great trade option And method of back door endearing humanity to other species! $\endgroup$ – John V. Aug 27 '19 at 18:23
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    $\begingroup$ Piggybacking on record-keeping are the notions of "notary", escrow, and arbitration services. When members of different merfolk clans/tribes want to do business with each other, there might be trust issues. Having a neutral arbiter who is obviously not a member of either clan in the transaction means they can do things like bring the thing they're selling to the clearinghouse run by the humans, knowing it won't be given over to the other party until they deliver their end of the deal, or that the other party has made a non-repudiable promise to deliver it, is very valuable to both parties. $\endgroup$ – Monty Harder Aug 28 '19 at 19:17
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    $\begingroup$ Nice point @MontyHarder. The service economy in action. $\endgroup$ – Cyn says make Monica whole Aug 28 '19 at 19:26

Trade Goods

What They Have...

  • Fish
  • Medicinal Underwater Plants
  • Psychotropic Underwater Plants
  • Transportation (storm-proof undersea barges)
  • Coral and Geodes
  • Nonferrous Metals
  • Shipwreck Cargo

What They Want...

  • Rustproof Metal Tools and Weapons
  • Bags/Jugs of fresh water
  • Buoyant wood - it is like anti-gravity to them
  • $\begingroup$ hadn't thought of some of those for the merfolk trading thanks! i really like the idea of the storm proof transportation. I was more looking for what the merfolk would 'buy' but new conepts are always welcome $\endgroup$ – John V. Aug 27 '19 at 17:00
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    $\begingroup$ @JohnV, thanks! I got lazy and didn't ready your entire question. Hope these changes are helpful $\endgroup$ – Henry Taylor Aug 27 '19 at 17:28

A pair other ideas about what merfolks could desire from surface people:

  • air: surface people could easily fill animal bladders or goatskins with air (they have lungs) and sell them to the merfolks: they could be used as entertainment (think of bubble fountains for the VIP parties) or to help lifting heavy weights underwater. Of course, if merfolk have lungs too, they could fill them on their own*, so, even if goatskins and bladders would still be useful, they would be of less value

  • transportation: swimming for long distances would be very tiring, and probably only the richest ones could afford to breed a dolphin or a giant seahorse to ride. But merfolk could easily pay for a lift on human ships: these could feature some kind of net (or even a small undersea cabin) underwater, where the merfolk can enter and wait for the ship to arrive near their destination

  • $\begingroup$ both very creative ideas thanks a bunch I really like both of those $\endgroup$ – John V. Aug 27 '19 at 17:52

Don't think too hard - just look at real life

In a way you kind of answered your own question. In real life we have lots of countries that buy/sell each other loads of things. In the past, we had barter, but many governments minted their own coin. This goes back to at least Ancient Greek times - the Chinese even had paper currency!

Alternatively, larger deals incorporated other things. For example, in exchange for a huge amount of gold and other treasures, the Pope once sent away Atilla the Hun's army. Plus, you even say that there are other kingdoms - the merpeople are not unified. I'm going to try and answer 2 questions at once: what do the merpeople want from humans, and what do the humans want from merpeople (I know you have the second part covered, but maybe you'll get some new ideas). So, a few things that can take place:

Currency: Merpeople pay for human goods with either gold/precious gems they find underwater, or even sand dollars! If they are a hierarchical civilization, I have no doubt that each kingdom has its own mining operation, and not all areas of the ocean are equally as bountiful. They'll also want to buy minerals and rocks from humans on land that are rare underwater for decorative reasons, capital, or other reasons.

Luxury/hi-tech products: Greek fire (fire that doesn't get put out with water) would be found easily in the land of merpeople but its secrets has been lost above ground. Souvenirs from shipwrecks are also possible - you can orchestrate entire deals with this if the ship is valuable enough. Rich merpeople would want to buy stuff that is common on land, but impossible to craft and grow underwater - like human architecture or palm trees. Paintings would be uncommon underwater as the paint would just go everywhere, so paintings would be popular purchases also.

Military support: Hire a mercenary navy. Imagine fighting a force that comes from under water and attacks you, and can't be drowned at sea - they're at home when they're at sea! Plus, they have greek fire, which means their ships might burn, but yours WILL burn! Tech inferiority or not, this is going to be terrifying. Rich humans will buy mercs from the ocean. The merpeople may also hire human mercenaries to kill any humans overfishing in their waters on land itself.

Food: Fish - obviously the cheapest and most consistent product can be sold to humans in return for all kinds of human food, like coconuts, various exotic meats like chicken and lamb, etc. It's just a matter of whether merpeople can digest it, and if they can afford it.

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    $\begingroup$ this is a big help thank you much! I especially like the idea for greek being explicitly a merfolk tech! $\endgroup$ – John V. Aug 27 '19 at 17:09
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    $\begingroup$ +1 for pointing out that if the merfolk are selling fish, they may want to buy meat/eggs/wool $\endgroup$ – Chronocidal Aug 29 '19 at 11:32
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    $\begingroup$ The military bit seems to be reversed - it is described as a service sold by merfolk, but the question asks about purchases by merfolk. Still, the idea could work in reverse. Steam ships require metal and coal to make and run, but they would greatly augment a merfolk navy. $\endgroup$ – MSalters Aug 30 '19 at 0:56
  • $\begingroup$ Yeah I tried to answer the question by taking both sides: what merpeople want and what they can sell. I also pointed out that merpeople may hire mercenary humans to kill other humans who are messing with their fishing waters and stuff. $\endgroup$ – cyber101 Aug 30 '19 at 13:57

Okay, I'm going to go there.


It's going to happen. You know it, I know it. Mermaids know it.

Professional mermaids say 'merverts' are making their lives a hassle

Can't have a believable economy without the oldest profession.

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    $\begingroup$ I think you are inverting this. The question was asking about what the Merfolk receive in exchange for their goods and services. If mermaid prostitutes are a thing, in what form would they want to get paid? Or do you mean that merfolk would like to offer pearls and fish in exchange for sexual favors of human prostitutes? $\endgroup$ – Philipp Aug 28 '19 at 11:00
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    $\begingroup$ Actually, thinking about it, that might not actually be that much out-of-character. A lot of mermaid legends are about mermaids luring people into the sea or onto dangerous cliffs with promise of sex. Maybe merpeople actually are more sexually attracted to humans than to each other, and so they would be willing to pay humans for sex? Maybe as human/fish hybrids they can not breed with each other but only breed with humans? That could explain why mermaids are so desperate for human men. It's the only way to ensure the survival of their (bastard-)species. $\endgroup$ – Philipp Aug 28 '19 at 11:07
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    $\begingroup$ They don't need to be more attracted to humans in general, just enough that some are. This will never be a whole economy, but depending on the target audience of the story it might make for some interesting plot points or just background. $\endgroup$ – Whelkaholism Aug 28 '19 at 14:10

Territoriality. They would want surface dwellers to stop doing certain things, or start doing certain other things.

Stop dumping that filth in the river! Whew! It really stinks. On the other hand, if you dump your raw sewage in this other river, it will nicely fertilize the commercial kelp beds.

Stop using drag nets to fish in this area. That's our garden for plaid weed, and your nets destroy it.


Various foods.


  • This matured and flavorsome meat would be highly valued by people who only have fish, crabs, prawns and sea-slugs as protein sources. Those who enjoy the ultimate acquired taste of the sea urchin, may also gain a taste for Fois gras.


  • Again a luxury meat which requires dry-air preparation, strong, rich flavor - a rare meat to be savored by the rich.

Chicken, beef, lamb.

  • These flavors are more for the common people of the sea, relatively cheap and available to the masses.

Herbs and spices.

  • There are many thousands of such flavors simply not available in the deep, where everything is just plain salty.

Boiled sweets.

  • Gobstoppers could provide a non-nutritious energy boost, various flavours might please, lemon, mint, strawberry, pepper - well who knows what might catch the mere-people's imagination and taste.

My first choice was going to be metal, but you've already mentioned that it's a limited resource for the land people. My second choice is decorated stone / statues, reasonining is pretty simple. I can't imagine weilding a hammer and chisle underwater being very efficient.

So for the rich merfolk they would commission pillars, statues and ornamants as the high end goods. For the more normal merfolk, probably not that far different from what the people want. They'd want different grains/berries/vegetables/meat/feathers/hides/furs.

this bit is a little fluffy as i'm not sure how it would occur. I'd imagine the greatest service they would like is to be able to record their knowledge, we write, I'm assuming the merfolk can't write, nor do they have the capability to.

  • $\begingroup$ thank you! the writing concept is something I never even considered! as for metal work I'm sorry I may not have been clear enough but on the surface they can use metal just fine its underwater where they struggle with metalwork so your suggestion there still stands $\endgroup$ – John V. Aug 27 '19 at 16:59

Freshwater fish. Living in the sea, this would be an otherwise unobtainable delicacy.



Just as the oceans have a bounty of medicinal fish and plants, so too does the land, in rainforests, deserts, all over. Obviously, merfolk would not generally be able to waltz deep into a rainforest to collect plants.


Given that merfolk have limited access to metals/tools, they would have a hard time quarrying anything but the softest rocks. However, powerful merfolk would clearly prefer a palace built from marble over one built from coral. This would surely be expensive beyond measure, but that only adds to the prestige value of the result. Conversely, merfolk would have better access to pumice and other volcanic rocks emanating from steam vents. As you know, pumice is valued on land as a light, porous rock useful for personal grooming, soil filler, etc.


Land walkers would surely have knowledge of principles and processes which occur more readily (or exclusively) out of the water. Because they lack the benefit of buoyancy, land folk have been forced to make heavier use of leverage, leading to wheels, levers, and the like. Conversely, merfolk would have much better, even intuitive understanding of fluid dynamics, including pressure, turbulence, laminar flow, venturi effects, and other things which are useful for building above-ground devices of varying complexity. Of course, they would describe these phenomena in medieval language, but that does not preclude a kind of formal knowledge of them which can be communicated across species.


Merfolk would be challenged to weave fabrics underwater. Perhaps they could use coastal areas to harvest reeds and fibrous plants, but surely they could not grow vast tracts of cotton and other textile plants, and looms would be exceedingly difficult to operate underwater. It would also be more challenging to tan and dry hides, and bringing leather hides underwater probably wouldn't be useful anyway. Plant-based clothing could likely survive and would surely have luxury value even if domestic merclothes were more practical.


On the one hand, we must ask: "What does a mertoilet look like, and how does it work?" Presumably, elimination simply occurs in some area where the currents take away and disperse the results quickly. On the other hand, most plants are growth-limited by the availability of phosphorus, nitrogen, and other elements commonly occurring in animal waste. It's possible that merfolk have domesticated large fields of seaweed, and that they fertilize them by also keeping their food fish in the same area, possibly also using the fields as their communal toilet.

However, water will tend to disperse nutrients, and simple tide action will guarantee that the water doesn't just sit still and let nutrients settle slowly over the course of hours. Perhaps merfolk learn how to fertilize seaweed manually by burying wastes in the seabed near the plants. If so, then one limit to seaweed yields will be how much "fertilizer" they can apply. While medieval Asians were applying "night soil" to their fields, this was far less common among Europeans, so it is plausible that your land walkers would rather sell their waste to the stupid merfolk than let it build up in their cities and cause disease. They could even build primitive sewer pipes that bring it directly down into shallow coastal areas, and thus a coastal landwalker and merfolk city could operate symbiotically.


I am going to go with another material manufactured via fire:

Coins of Glass

I could see Coins of Glass being a legitimate currency. Because it is an item that can be only be crafted by humans, the rarity of it would be its value -- MUCH more valuable than all that cheap gold we have lying around the sea-bottom.

Of course merfolk wouldn't realize that glass actually comes from sand.

In addition, clear glass will almost appear magical underwater as it would be nearly invisible.


Military: Mercenaries, weapons, training, logistics (e.g. canned food), technology, etc

Quality of live: Jewelry, technology, glassware, food, art, literature, etc

Production: Technology, tools (e.g. steel mining picks), machines, slaves, etc

Services: Companionship, banking, outsourced prisons, education, performances, etc

Abstract: Alliances, land ownership, investment, mining rights, etc.


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