Peppermint shrimp (Lysmata wurdemanni) are primarily useful because they eat a common nuisance in reef tanks: the glass anemone, Aiptasia. There are also some reports that they help control flatworm populations, including Acropora-eating flatworms.
These shrimp are compatible with most other inhabitants of a typical reef tank, although large predatory fish will happily eat them. Some reef keepers have reported peppermint shrimp nipping on corals. Despite these isolated reports, our experience has been that these shrimp provide a safe and effective approach for managing Aiptasia.