I've had very good luck here with fish for coyotes. But, I have also learned to have some "variety" on hand, too. Seems like some years fish was the ticket, then others they wouldn't touch the stuff and only went for something else like 1/4 of a bloody muskrat carcass tainted, or ground meat bait, etc. Then the following year fish seemed to be the ticket again.
Consistently I've had best luck with fish, but I also use a lot of commercially prepared bait, too. The experience behind many of the good recipes available commercially is hard to beat.