Dog Allergies Treatment

My dog has food allergies amoung other things that she is allergic to. I’ve switched her to a venison and rice formula about 2 or 3 months ago because its hypoallergenic. Ive been reading up on this for a while, and ive heard some suggestions about a fish formula.. could this possibly be better than the venison?? and if so, is it bad to continue switching her food?? Thanks in advance! =]