Acclimation: never lift the worm out of the water, as air can get trapped in its tube; move it in a bag, under water. When buying, pick a specimen with a complete crown that withdraws briskly when touched, and whose tube is neither torn nor broken. Invertebrates cope poorly with changes in water quality: bring the bag water to your tank's water slowly.
Setup: this is the key point. Clusters are torn from their base when collected and do not reattach by themselves in aquariums, which is why most die within weeks or months. Glue the base of the cluster to a rock with cyanoacrylate gel (the glue used for coral frags); attached this way, they are long-lived. Place it in moderate flow, in the shade of an overhang as in the wild.
Tankmates: these worms do not sting, do not eat other animals and do not compete with them chemically. The reverse is not true: butterflyfish relish their crowns, some wrasses and hawkfish eat them, as do triggerfish, large puffers, filefish and some angelfish; omnivorous crabs kill them by pinching the tube, and eels or urchins can damage them as they move about.
Crown loss: many feather dusters shed their crown from time to time. Do not remove the tube: the crown grows back within a few weeks. An occasional loss is nothing to worry about; if it happens every couple of months, look for an irritant or a lack of food. A starving worm drops its crown and grows a smaller one each time, so a shrinking crown means it is not getting enough food. Invertebrates do not tolerate copper medications.
Brittle stars: generally harmless, they may still pick apart a newly added colony that smells of your food-scented fingers.
