As I understand it, it has more to do with the intensity and duration of the light than most other things, other than of course; optimum temperatures. Roses for instance, and many other lifeforms, can be tricked into changing there biological clocks by adjusting the amount of light and temperature of their surroundings. I can't remember his name but an aquarist got a pair of Green Terrors (a kind of S.American Cichlid, fish) to breed 6 times in 1 year by playing with temp and photoperiod. If you put your fish near a window, I'd bet they'd spawn within a week of the fish in the nearest lake if you made the water temp the same.
Tight lines,
Wade