Dead colt coral...now what?

[Beverly]

Mike,

What kind of water flow is it getting? How's the alk, Ca, Mg and pH swings in the tank?

If it has now securely attached to the rock it's on and it doesn't improve over the next week or so with moderate water flow and excellent water chemistry, I would be tempted to cut it off just above the base. Doing this will remove the not-doing-well portion, but leave a base from which a new colt can grow. I've done this with xenia and devil's hands and within a month, the new corals show signs of growing back.