This is how my Excel document began:



And after that I added a more visual representation showing the house, occupants, etc:

 

Channeling Neo:

"There is no fish."

Yes, there is no mention of any fish, so no one owns a fish. That took me about a minute.

 

I solved it in 10 minutes. Maybe I figured out the right order to solve it?

 

Yes, there is no mention of any fish, so no one owns a fish. That took me about a minute.

See the title of the puzzle, namely "Who owns the fish."

The lead in material states that each person owns a particular type of pet. There are five people. The clues (and that's all they are, are clues) only mention four pets, none of which is a fish. So, ergo, the fifth pet, which must exist to satisfy the constraint that each person owns a particular type of pet, is a fish.

 

Hi,

I used to love to solve these problems. I used to buy books for about a dollar and they contained a whole bunch of these kinds of puzzle ranging in level of difficulty, and i think they still sell them.
There are tricks you can use like converting "If then else" statements into pure boolean logic statements, and solve it using boolean logic.

Been a long time since i did any of these, because i learned that it is more time wise to study something that will have a real benefit, like electronics
Circuit analysis can be a puzzle if you want to take it that way, and you can learn something useful by analyzing every circuit you can find. I bought books, some with hundreds of circuits in them, bigger and thicker than phone books, and tried to analyze each and every one. All in all i probably did a million circuits over the years, and each one is like a puzzle in itself if you choose not to use automated circuit software. Back when i started there was no automated software so it took a lot of hand work and thinking.