Check the immediate basics
Remove the dead shrimp and inspect the body without assuming a particular disease. Test ammonia and nitrite, verify temperature, and confirm that the filter is running.
Review recent additions: new plants, fertilizers, medications, cleaners, water changes, or a new shipment can help narrow the timeline.
Look for a pattern
A single older shrimp may die without an obvious tank-wide problem. Multiple deaths, especially with lethargy or failed molts, deserve closer investigation.
Avoid treating the whole aquarium based on a visual guess. Record readings and changes, and seek experienced invertebrate guidance if losses continue.
For your own tank
Write down the date, test results, and any recent product or livestock addition. A timeline helps an experienced keeper assess the situation. If deaths continue, include tank size, filter type, source water, and maintenance history when asking for help.
Use these as general hobby references. Test your aquarium and confirm product guidance before making changes.