I have been thinking of a setting that involves a person getting stranded in a temperate forest that has not been previously inhabited. He eventually meets other people but until then he has to survive with what he has.

He has little knowledge on how to forage but, due to a quirk of his situation, he can regularly obtain large amounts of fresh fish. He also has three pieces of potatoes with him along with some knowledge of how to grow them. I'm trying to figure out if this person could survive indefinitely on a diet of only those two things, but I'm wondering if nutritional deficiencies will eventually catch up to him.

Edit: I'm considering having them be willing to eat raw parts of the fish.

  • $\begingroup$ This question could be off-topic here as too story based, you might get an answer or two though. I'm trying to figure out if it might be tailored to fit the Medical Sciences stack. but they don't really specialize in nutrition, the Veganism & Vegetarianism stack could possibly handle it, but you'd need to read the terms, and consult the help center there to figure out how best to post. Best of luck. $\endgroup$ Commented Jul 8, 2019 at 1:07
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    $\begingroup$ @Confoundedbybeigefish. I think asking on a vegetarian stack about a diet consisting almost entirely of fish is a good way to get a closed question. I find it hard to believe that this person would not be able to find anything else to eat. Berries are a gamble, even if birds eat them, but there should be other fruit. Or vegetables or herbs. Something he recognizes, or can see that other animals eat and then try a small bit. Fish is fine for his protein, fat, and caloric needs, plus several micronutrients. Potatoes take a long time to grow but will also add some nutrients and calories. $\endgroup$
    – Cyn
    Commented Jul 8, 2019 at 1:53
  • $\begingroup$ indefinitely? No. Fish and potatoes give you everything you need. It's a sushi where you replace carbs source "rice" with "potatoes". Also raw potatoes is dangerous. So if you have potatoes you need to cook them before consumption, thus it make no sense to eat raw fish. $\endgroup$ Commented Jul 8, 2019 at 8:34
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    $\begingroup$ @SZCZERZOKŁY, you made fish&chips and sushi too dangerously close now ;) $\endgroup$
    – L.Dutch
    Commented Jul 8, 2019 at 9:16
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    $\begingroup$ @L.Dutch Sushi is just Fish & chips for people who are avoiding fats :) $\endgroup$ Commented Jul 8, 2019 at 10:44

2 Answers 2


Premise: I'm not a nutritionist, so I might be missing something.

That being said, I think you should be able to survive and be reasonably healthy on fish and potatoes alone. Cooked fish would give you most nutrients you need, and potatoes would pitch in with the main thing you would lack: vitamin C.If they have plenty of both foods, they should be ok. Unless absolutely necessary, I would avoid eating raw fish, due to the chances of getting a parasite.

On a side note, consider the growth time of potatoes. Assuming the climate allows for a good harvest, it takes about 10 weeks to grow some decent sized potatoes. Starting with only 3 pieces, might not be enough to plant and eat for those 2-3 months.

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    $\begingroup$ What do far-north tribes do about vitamin C? Not many lemons growing on the north shore of Alaska. If I recall, the main thing they do is eat every part of the animals they catch, particularly the liver and kidney. Supposedly that gets them vitamin C, as well as several other nutrients usually associated with fruit and veg. Not sure if the same applies to fish internal organs. Also, some carnivores have livers that you must be cautious about eating because they have concentrations of a particular vitamin that can be toxic. E? D? Not sure. $\endgroup$
    – puppetsock
    Commented Jul 8, 2019 at 14:04
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    $\begingroup$ Yes, liver contains vitamin C, but you would have to catch large fishes or some other large animal (like seals in your example). So in a real survival situation, and without anything else, that's your best bet to avoid scurvy. But since he is planning to give them potatoes, there's no need to eat raw liver and risk to catch something. (Not sure about which toxins and in which quantity you would get, but yeah that's a risk too) $\endgroup$
    – Mr_Bober
    Commented Jul 8, 2019 at 15:07
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    $\begingroup$ Northern sources of vitamin C are cranberries, lingonberries, etc. If no berries are around, pines and firs are your friend: you can eat newly sprouted needles, or chew on inner bark (it is soft), make tea from mature needles. But our OP is in temperate zone, so berries are definitely available, and there is very little risk in trying to eat a single berry. $\endgroup$
    – Bald Bear
    Commented Jul 8, 2019 at 20:21
  • $\begingroup$ Raw fish, meat, and fresh blood have decent amount of vitamin C ; see for example discovermagazine.com/2004/oct/inuit-paradox $\endgroup$
    – arp
    Commented Jul 13, 2019 at 21:12

A supplementary answer on the question of vitamin C.

Contrary to our modern ideas about vitamin C, you don't need much to stave off disease, and just about all fresh food contains some. Anywhere from 40 to 100 mg/day is currently recommended, even less will stave off diseases due to deficiencies. Signs of deficiency take weeks to start showing allowing your protagonist to go for long periods of time without fresh food and still be fine so long as they got some later.

In particular pine needles are high in vitamin C, and pine needle "tea" is a common way to stave off vitamin A and C deficiencies. But it doesn't sound like your protagonist would know about that, nor be very adventurous. Survival stories are full of people being malnourished and starving in the middle of a bounty they cannot recognize. That's ok, potatoes and fish, even cooked, contain enough. So long as your protagonist is eating any fresh food, and not boiling the hell out of it, they're fine.

The problem with vitamin C is it's very fragile and degrades quickly. Sailors on long voyages would be getting no fresh food whatsoever for weeks, often not even fish. It would all be dried, salted, and boiled destroying all the vitamin C. Lemons and citrus were used because they contain so much vitamin C they'll still remain beneficial after weeks at sea with no refrigeration.


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