If someone adds millions of small fish to a lake , how would the number of big fish change?

The big fish would have more to eat, so they would produce more fish because they have more food to feed them with.

Well, if the big fish are predators, then more food for them and their population would increase greatly. If the big fish and small fish have the same type of food, then that means that the big fish, hypothetically, would have millions of new contenders for their food source. That means that it's very likely that many of those big fish would die out.

Brother ur in collage do it yourself or i will tell prof. mike