You don't really need dailly water changes but you DO need to simulate seasonal changes...either with the water LEVEL as suggested or with IRREGULAR large (50% range) water changes.
I also need to back John and Dread up on the Hormone issue. This is another seasonal trigger that can indicate to a fish that others in the river or lake are spawning. Adding water from another tank housing a spawing pair or even just fry has been know to stimulate breeding. Altering the light intervals (lengthening generally) can also help stubbern cases.