Understand what shrimp graze
Biofilm is a thin community of microorganisms that develops on surfaces in an established aquarium. Shrimp pick at it on leaves, wood, rocks, and filter media throughout the day.
This natural grazing is especially valuable to tiny shrimplets that may not reach larger food pieces. A tank can look clean while still supporting the surfaces shrimp need.
Protect useful growth
Avoid scrubbing every surface spotless or replacing all filter media at once. Clean visible debris selectively and preserve established biological media.
Biofilm does not excuse overstocking or poor water quality. Continue testing and feeding appropriately; the goal is a mature, balanced aquarium, not an unmaintained one.
For your own tank
Let a new aquarium mature before expecting every surface to support a large shrimp colony. A thin natural film is different from a tank that has accumulated rotting debris. Preserve useful surfaces while still removing decaying material and monitoring water tests.
Use these as general hobby references. Test your aquarium and confirm product guidance before making changes.