I'm guessing you're pretty young or new to fishing. Lots of us have asked that kind of question before. But you will find that outside of gigantic bodies of water, people aren't willing to give away good fishing lakes/ponds, and creeks/rivers.
As you spend more time fishing and more importantly, more time exploring and succeeding, you then realize why that information isn't just given away.
Anyway, much of Caledon's lakes and ponds are private. Couple obvious spots open to the public if you google it. And Brampton has spots too.
But it all depends if you're fishing from shore or boat, or wading rivers. And depends on what you're targeting.