The Free On-line Aquaculture Dictionary

Photoperiod Control of Rainbow Trout Broodstock
Photoperiod control can be used to advance or delay the spawning process of many salmonids. A schedule or advancement and retardation of Rainbow Trout spawning is given.
General Rules Delayed Spawning Advanced Spawning
 

General rules of photoperiod control for rainbow trout are shown below. The yellow and black areas represent the percentage of light and dark (respectively) each day that is experienced by the fish.