Identify the Changes in Fish After Death 1. the color starts to fade until it becomes dull as spoilage progresses 2. characterized by the stiffening of the muscle tissue. This state lasts only for a few minutes in some fish to several hours in others. the fish in this state is considered fresh. 3. the breakdown of tissues caused by enzymes. Since it softens the tissue, it proves the activity of microorganisms. 4. the state when the components of the flesh are assimilable forms. It is accompanied by a foul odor, which is the result of the breakdown of protein. 5. The fish at this stage is spoiled and undesirable.​