A lot of aquarium keepers have discovered various creatures in their tanks that they did not intentionally introduce. These hitch hikers can be both beneficial and harmful, but almost all of them are creepy looking. The bristleworm is no different. It has sort of an undeserved bad reputation, though some related aquarium worms are very harmful, and many people hate to see them in their tank. There are a few invertebrates out there that will eat bristleworms, and the arrow crab happens to be one of them. Though I do not personally like arrow crabs because they can and will eat small fish and various other beneficial invertebrates, they could certainly help keep any unwanted bristleworm population in check. Below is a neat video from Reef Scavengers of an arrow crab doing just that…making a meal out of a bristleworm.
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