This studywas conductedfrom November2024 to March 2025in theFish Nutrition Laboratory, Faculty of Fisheries and Marine Sciences, Universitas Riau. The objective of this research was to describe changes in digestive enzyme activity (protease, amylase, and lipase) and intestinal histology of Asian Redtail Catfish (Hemibagrus nemurus) fed diets containing fermented catfish offal flour using EM-4. …