New Rod...
You can get a super rod in sapphire by going to mossdeep and then go up the steps to a house and talk to the fisherman.
you get the good rod from a man at a dock near Solaceon town go south and hes on a dock.. Answer his questions say yes and he'll give you the good rod. Note: This for Diamond and Pearl
Talk to fisherman on route 118
Talk to someone on either route 32 or 34