House Puzzle: Who Has Fish?

1. Statement of the riddle▲

- There are 5 houses lined up in different colors.
- In each house lives a person of different nationality.
- Each person drinks a beverage, has a means of transport and raises a different animal.

Here are 15 facts about these homes and their residents:

01. The Canadian lives in the red house.
02. The Swede has a dog.
03. The Dane drinks tea.
04. The green house is located just to the left of the white house.
05. In the green house, the one drinks coffee.
06. The one who uses snowshoes has a Great Grey Owl.
07. In the middle house, the one drinks milk.
08. In the yellow house, the one uses a sled.
09. The Norwegian lives in the first house.
10. The one who uses a helicopter has a neighbor who has reindeer.
11. The one who has snow geese has a neighbor who has a sled.
12. The one who travels by ski drinks beer.
13. The Norwegian is a neighbor of the blue house.
14. The Finn uses ice skates.
15. The one who uses a helicopter has a neighbor who drinks water.

Question: Who has fish?

This riddle is a variation of Zebra Puzzle where cigarettes have been replaced by the means of transportation. I read it in a book entiled in French “Escape Game. Calendrier de l’Avent.” (Escape Game. Advent Calendar. in English) during December 2024.

Note: the authorship of the enigma would be an urban legend, like the assertion that only a tiny part of the population would be able to solve it (objectively not very credible indeed).

2. Modeling the puzzle for its resolution▲

For each of the 5 houses, we have 5 characteristics with 5 possible values:
Color: red, green, white, yellow, blue.
Nationality: Canadian, Swedish, Danish, Norwegian, Finnish.
Drink: tea, coffee, milk, beer, water.
Means of transportation: snowshoes, sled, helicopter, skiing, ice skates.
Animal: fish, dog, great gray owl, reindeer, snow geese.

The modeling that I propose to solve this enigma consists of a table with 6 rows and 6 columns. The rows list the different possible characteristics for each house. The columns list the 5 houses. The resolution is then done step by step by crossing out the values ​​that become impossible by reading and deducing the 15 pieces of information written in the statement of the puzzle.

3. Step by step resolution▲

We read the information provided by the statement and deduce what we can update as knowledge in the table that models the puzzle. After using and inferring all the data, we can then answer the question of the enigma. A progress report on the resolution of the enigma will be carried out each time we have found a characteristic for all the houses (i.e. complete knowledge of a row of the table). Full speed ahead!

Note: in the table, the step at which the inference could be established (Edd) is indicated next to the data, in parentheses, E03 for example.

3.1. Discovery of the color of houses▲

1. Nothing can be crossed out after reading the first 3 pieces of information.
2. After reading information 04. The green house is located just to the left of the white house, you can cross out the white word in house 1 and the green word in house 5.
3. After reading information 05. In the green house, the one drinks coffee., you can cross out the word coffee in the House 5 column.
4. After reading information 06. The one who uses snowshoes has a Great Grey Owl., no characteristic values ​​can be crossed out.
5. After reading information 07. In the middle house, the one drinks milk., you can cross out all drinks in house 3 except milk. In all other houses, you cross out the word milk in the Drink line.
6. By deduction of information 05. In the green house, coffee is drunk., we can cross out the word green in the House 3 column.
7. After reading information 08. In the yellow house, a sled is used., we cannot cross out anything.
8. After reading information 09. The Norwegian lives in the first house., we can cross out all nationalities in house 1 except Norwegian and cross out the word Norwegian in the other House columns.
9. By deduction of information 01. The Canadian lives in the red house., we can cross out the word red in the House 1 column.
10. By deduction of information 02. The Swede has a dog., we can cross out the word dog in the House 1 column.
11. By deduction of information 03. The Dane drinks tea., we can cross out the word tea in the House 1 column.
12. After reading information 10 and 11, we cannot cross anything out.
13. After reading information 12. The one who travels by ski drinks beer., we can cross out the word ski in the House 3 column.
14. After reading information 13. The Norwegian is a neighbor of the blue house., we can update the Color row for each House column by crossing out all the other colors in the House 2 column and the word blue in the other House columns.
15. By deduction of information 04. The green house is located just to the left of the white house., we can also cross out the word green in the House 1 column. (The house to its right is not white). Therefore, we deduce that the color of house 1 is yellow. We can then cross out all occurrences of the word yellow in the other House columns.
16. By deduction, we can cross out the color white in the House 3 column because the color of house 2 is blue and not green.
17. Therefore, we deduce that house 3 is red. We can cross out the color Red for the other houses.
18. Therefore, we automatically deduce that house 4 is green and house 5 is white.

At this point, we know all the colors of the 5 houses:

• House 1 is yellow,
• House 2 is blue,
• House 3 is red,
• House 4 is green,
• House 5 is white.

3.2. Discovery of the drinks consumed by the inhabitants of the houses▲

Let’s continue solving the riddle by using the information from the statement again.

19. After reading information 14. The Finn uses ice skates., we can cross out ice skates in the House 1 column.
20. After reading information 15. The one who uses a helicopter has a neighbor who drinks water., we cannot cross anything out.
21. We return to the first information 01. The Canadian lives in the red house. We know that the Canadian lives in house 3. We can cross out the other nationalities in house 3 and the word Canadian in the other houses. We can cross out the word dog in house 3 because it is owned by a Swede (information 02. The Swede owns a dog.).
22. After rereading information 03 and 04, we cannot cross out anything.
23. After rereading information 05. In the green house, coffee is drunk., we can cross out the other drinks in house 4 and cross out coffee in the other houses. We can also cross out the word Danish in house 4.
24. After rereading information 06 and 07, we can’t cross anything out.
25. After rereading information 08. In the yellow house, the one uses a sled., we can cross out the other means of transport in house 1 and cross out the sled in the other houses.
26. After rereading information 09 and 10, we can’t cross out anything.
27. After rereading information 11. The one who owns snow geese has a neighbor who has a sled., we can deduce that the snow geese are in house 2. We therefore cross out all the other animals in house 2 and “snow geese” in the other houses.
28. By deduction of information 02. The Swede has a dog., we can cross out the word Swede in house 2.
29. After rereading information 12. The one who travels by ski drinks beer., we can cross out the drink beer in house 1 because the sled is used. We deduce that the Norwegian living in house 1 drinks water. We can cross out the drink water in the other houses.
30. After rereading information 13 and 14, we cannot cross out anything.
31. After rereading information 15. The one who uses a helicopter has a neighbor who drinks water., we deduce that the means of transport of house 2 is the helicopter. We cross out the other means of transport of house 2 and we cross out the word helicopter in the other houses.
32. By deduction of information 14. The Finn uses ice skates., we know that a Dane lives in house 2. We can cross out Finn in house 2 and Dane in the other houses.
33. By deduction of information 03. The Dane drinks tea., we can cross out the drink beer in house 2. We deduce that in house 5, we drink beer.

At this point, we know all the drinks consumed in the 5 houses:

• Water in house 1,
• Tea in house 2,
• Milk in house 3,
• Coffee in house 4,
• Beer in house 5.

3.3. Discovery of the nationalities of the inhabitants of the houses▲

Let’s continue solving the riddle by using the information from the statement again.

34. After rereading information 12. He who travels by ski drinks beer., we know that skiing is the means of transport of house 5. We can cross out the other means of transport in house 5 and the word ski in the other houses.
35. By deduction of information 14. The Finn uses ice skates., we know that the Swede lives in house 5. By deduction, we therefore know that the Finn lives in house 4.

At this stage, we therefore know all the nationalities of the people living in the 5 houses:

• A Norwegian lives in house 1,
• A Dane lives in house 2,
• A Canadian lives in house 3,
• A Finn lives in house 4,
• A Swede lives in house 5.

3.4. Discovery of the means of transport used by the inhabitants of the houses▲

Let’s continue solving the riddle by using the information from the statement again.

36. By deduction of information 14. The Finn uses ice skates., we know that the means of transport of house 4 is ice skating. We deduce that snowshoes are that of house 3 (the one that remains).

At this point, we know all the means of transport for the inhabitants of the 5 houses:

• The sled for house 1,
• The helicopter for house 2,
• The snowshoes for house 3,
• The ice skates for house 4,
• The ski for house 5.

3.5. Discovery of the animals of the inhabitants of the houses and final deduction▲

Let’s continue solving the riddle by using the information from the statement again.

37. By deduction of information 02. The Swede has a dog., we can cross out the other animals in house 5 and the word dog in the other houses.
38. By rereading information 06. The one who uses snowshoes has a Great Grey Owl., we know that the Great Grey Owl is in house 3. We can cross out “Great Grey Owl” in the other houses.
39. By rereading information 10. The one who uses a helicopter has a neighbor who has reindeer., we deduce that the reindeer are in house 1. We can cross out the other animals in house 1 and the word reindeer in the other houses.
40. By final deduction, we note that the fish are in house 4, where the Finn lives.

Finally, we also know all the animals for the inhabitants of the 5 houses:

• Reindeer for house 1,
• Snow geese for house 2,
• Great gray owl for house 3,
• Fish for house 4,
• Dog for house 5.

3.6. Final table of the resolution of the enigma▲

4. Solution to the riddle▲

So the riddle question Who has fish? can be answered: The Finn has fish. He lives in the green house number 4, drinks coffee and gets around on ice skates.

Sonia Kanclerski, Pause-café chez Sonia, article House Puzzle: Who Has Fish?, 20/01/2025.

5. To learn more about this riddle▲

I share two links (in French) that deal with solving this type of puzzle:

• Presentation of 2 resolution methods (resolution by pure reasoning and resolution by integram): http://villemin.gerard.free.fr/Puzzle/Enigme50.htm
• Einstein’s Enigma: An Open Problem : https://segpa.org/lenigme-deinstein/