Certified GKH Gardening Expert
You could make your own fish emulsion to fertilize your plants. Simply put some fish remains in a -5-gallon bucket filled about 3/4 full with water. Stir well and allow it to sit for a day or two, stirring occasionally. (Be sure to place it somewhere well away from animals.--If you have a lid to put on it, that would help too.)
In a couple days, you can strain out the fish emulsion by tying a piece of cheesecloth over the top of the bucket and pouring the liquid into another container. This liquid can then be used to water and fertilize your peony plants.