How do you tell where the fish are in a lake?

Find irregularities along edges that concentrate fish.

Look for the tip of a long point extending into the lake, where it suddenly drops off into deeper water.
The general edge of weeds attract fish. ...
Places where timbers cross or form small gaps can hold fish.

Why do fish go to the bottom of a lake?

Because warm water sinks in very cold freshwater, fish in these water bodies often gather in groups near the bottom. Some species, like koi and gobies, may burrow into soft sediments and go dormant like frogs and other amphibians, but most fish simply school in the deepest pools and take a winter rest.