cowfish cautions

[Aquamarina]

Hi. I'm a newbie to salt water fish-keeping, but am becoming fascinated by the hobby. We bought this house in Nov.02 and it came with a stocked 220 gal salt tank, so have had to learn quick! So far, so good, until I decided to buy a few more fish--2 Tangs, a butterfly, a blenny, and a long-horned cowfish about 3" long, just because he seemed personable! I followed the instructions from the fish store owner, giving them a bath in the prescribed chemical, and put more chemical in the 20-gal quarantine tank and added the fish. Next morning, all were dead, except the cowfish, which I was told "should have been first to die". Looking to the internet for answers later, I discovered that a frightened or sick cowfish can excrete a toxin which can wipe out a fish tank. As he was the only fish left alive, it is only logical to assume that he was the murderous culprit!
Before I found this out, he was put in the main tank so hopefully any toxin will be somewhat diluted. I keep the salt mixing tank in readiness, though.
Another problem has come up--3 days ago, the cowfish "Apollo" (because he looks like he is on a moon mission!) got stuck in a rock cave 3' down at the bottom of the tank, and just floated looking out the glass, making little attempt to find the way out. After missing feeding time, I began to worry that he would die in there and start producing toxin, so I started to chip away at the rock with a steel yard-stick (hoping not to frighten him!) and eventually freed him. Because of this inability to slide in and out of crannies like other fish, and because a dead cowfish would be difficult to remove from rocky formations, I don't think it's a good idea to have cowfish in large tanks with a lot of rock.
I do like him, though, and think he is such an interesting fish. I am posting this rather long (sorry!) message just as a caution to other fish-keepers who might be considering cowfish. I won't be buying any more fish without getting as much info on them as possible!