Why should fish be added last in a reef aquarium?

Robert, I just read your site and thought it was so informative. Four months ago I lost all ( nigar trigger, clown trigger, tomato clown, yellow tang, lion fish, and 3-strip damsel ) from a puffer. I believe it was diseased. I had all fish for at least 3 years who no problem. Except for the puffer, which was purchased last.

I've recently just started another set-up with a yellow tail damsel and a blue damsel. Here's my question: Even though you've written, fish should be added last (in a reef tank). Is this a must ? If so, what's your reason behind this?

Its because of the cycling process... Hobbyists often try to get the tank "looking" good. This usually may mean adding fish or coral and because of cost, not all the live rock.

They then add a significant amount of live rick which creates ammonia nitrite... and usually stresses or kills the fish.

So if you were planning a reef tank (live rock)I would recommend my advise on cycling.