I have not been able to find in the regulations any resources on daily fishing hours, daylight to dark?
Are there differences for Lakes, Rivers etc..
There are no set fishing hours for steelhead, so you could fish 24 hours per day.
The only species of fish with set fishing hours are anadromous Chinook Salmon. Check annually for Chinook seasons, usually set by the Idaho Fish and Game Commission in March or April, for the listed fishing hours.