Coco worm?

Hey guys
I have had a coco worm for a couple months now and he was great...was always out during day time with a huge crown.

Then I noticed my powder blue tang would peck at him while he was out...

Now, he only comes out at night, and his crown is much smaller...did he lose his crown and grow a new one? Any idea if these guys do this? I cant think of another reason why it would be so much smaller....

Does anyone have experience with coco worms they can share?

 

http://wetwebmedia.com/featherfdgfaqs.htm
http://www.wetwebmedia.com/featherbehfaqs.htm
Tangs are known to pick at the casings of the worms so protecting it with rockwork or removing one or the other may be necessary.Diet and in particular the size of the plankton offered is most important.
Filter feeders like these require alot of work ime.