Is it ever to late to fight for child custody?

I once read that you must fight for any type of child custody before the child reaches the age of two or you lose all rights. Is this true? If so are u still entitled to pay child support?

I think you can fight for custody until the child is 18 but the child could decide who they want to live with at the age of 14. The older the child gets though the harder it is on the child because the courts will have a person come out and ask the child questions thus putting the child in the middle of it and making the child choose between the parents, the bill for this process is on you and adds up very quickly.