Corals & Invertebrates: Reef Tank Care Guides

It's less about the species itself and more about what it eats and how it behaves at scale. Many animals that arrive as hitchhikers on live rock — amphipods, copepods, certain worms — are the same general category of small invertebrate that's deliberately purchased as 'cleanup crew' (amphipods and pods, in particular, are often beneficial rather than problematic). The animals that get a 'pest' label are usually ones that eat things you don't want eaten — aiptasia anemones that sting corals and fish, or hermit crab species that outgrow their reef-safe reputation and start preying on snails and coral polyps. The same tank can have both beneficial and problematic hitchhikers at once, which is why identification matters more than a blanket reaction to 'something new showing up.'

Coral dipping is a widely recommended step for new coral frags specifically, mainly to address hitchhiking pests (like aiptasia) that can arrive attached to a frag's base rock or skeleton — covered in more detail in our coral dip and aiptasia guide. For cleanup crew invertebrates (snails, crabs, shrimp), a full quarantine tank is less commonly used than for fish, partly because many inverts don't tolerate quarantine medications well, but a visual inspection for hitchhikers before adding anything to the main tank is a reasonable minimum step regardless of species.