[Quinn]

Bah. There is no such thing as bad in the animal kingdom, there is only survival.

Some crabs may consume desirable organisms ranging from microcrustaceans through to corals and fish, others may not. It is difficult for us as hobbyists to postively identify the majority of these hitchhikers. Some people feel that it is beneficial to remove such crabs regardless before they do any damage.

These animals do fine in sumps or overflows, and I think we at least owe this much to them. It's rather ironic that these creatures survive a trip of several thousand miles in a stuffy cargo hold only to be flushed down a toilet. Personally I have decided to leave all hitchhikers until I have evidence that indicates that they should be removed, in the tradition of due process (if Paul Bernardo gets it, why shouldn't a crab living in a hole with my blenny?).

Every macroorganism on the planet consumes other organic material to survive. It just so happens that some crabs have adapted to eat a wide variety of foodstuffs, and hence become a scapegoat when something goes wrong in someone's tank.