a little anicdote of mine... when I first started my tank I put in three yellow tails. They were quite fine for a while then one seemed to "give up" and was always on retreat. At that point it seemed like the others harassed this one even MORE. It was almost as once he gave up the others wanted to get rid of him (a survival of the fitest instinct perhaps) I came home from work the one day to find the pacifist barely able to keep himself afloat. I was able to scoop him up and put him in a HOT quarentine with some fake plants to give him something to hide in. Future feedings into the tank went into the quarentine then what he didn't eat trickled down into the rest of the tank where the others got it. He managed to make a full recovery! I have named him lucky, sold the other two yellow tails back to the LFS
that sold them to me! :o) I figured if I was going to keep a damsel in the tank I wanted the pacifist.
Here's lucky and his tail: