Answer:
Coal.
Explanation:
Fish can reproduce to make more.
Wood can be obtained by growing trees.
Now we're down to soil and coal. Soil cannot be created like water, but it is a substance that is almost endless.
As for coal, it cannot be created but for thousands of years.
Your answer is coal.
Coal.
Fish can reproduce.
Trees can be grown for wood.
Soil is something that is everywhere, and we won't run out for a long time.
For coal, you have to wait thousands of years.
So the answer is coal.