Two men caught 36 fish; x caught 5 times as much as y. how much fish did y catch?

Let's assume y caught y fish.

According to the given information, x caught 5 times as much as y, so x = 5y.
The total number of fish caught is x + y = 36.
Substituting the value of x from the second equation into the first equation, we get 5y + y = 36.
Combining like terms, we get 6y = 36.
Dividing both sides by 6, we get y = 6.
Therefore, y caught 6 fish. Answer: \boxed{6}.