Can you use isinglass as a fertilizer?

Yes, isinglass, which is derived from fish bladders, can be used as a fertilizer due to its high collagen content and nutrient-rich properties. It can improve soil structure and enhance microbial activity. However, its use is not as common as other organic fertilizers, and it may not be suitable for all gardening practices. Always ensure it aligns with your specific gardening needs and practices.