Here is a quick tip to consider if you are going to try and frag a coral from your tank.
First a quick definition: frag, I believe is a short-hand term for fragment. Most coral species can reproduce from fragments, or frags. Therefore a small piece of a coral colony is a frag and the action of fragmenting a coral is called fragging. Tired of the italics? Good, I am too, so I won’t italicize the word anymore. Now that I’ve introduced that odd term, just accept it. A small piece of a colony that breaks off and settles in a suitable environment can grow into an entirely new colony. In nature, this process happens naturally by some environmental stresses.
Something to seriously consider, however, when trying to frag a coral from your display tank, is that many corals release harmful toxins when stressed, and I can’t think of anything more stressful than the notion of someone or something trying to break me apart into tiny pieces and see if I will grow. How’s that for projecting my human emotions onto the coral.
Frag corals outside of your tank
My point isn’t to discourage you from doing it–it’s fun and works great. I do want to caution you however about those toxins. Whenever you attempt to frag a coral from your display tank, remove the entire rock that the coral is attached to, and frag it in a container separate from the main tank. Active propagation in a separate container can help protect the inhabitants of your display tank and will also make it easier to collect and attach the fragmented pieces. After the fragging is complete, allow the coral specimen to recover in a second container, filled separately with water from the display tank. Never pour used water from the propagation containers back into the display tank. Also, just to be safe, consider running activated carbon after any fragging activity to add a layer of safety for fellow tank-mates.