| Usually SW fish are more interested in chaseing the intruder out of their territory. They usually don't kill something unless they plan to eat it. For a fish causing the problem, usually I'd expect to see a beat up fish after a day or so, not a death after 3 or 4 days.
This leads me to suspect that there is something else going on here.
Many years ago, about 30, I had a similar problem. My existing fish did fine, but any new fish died. This happend right at the time when many Pacific Ocean fish became easily available. I don't know for sure, but I suspect that problem was the massive use of cynaide that was being used to catch fish back then. This was so bad for awhile that I gave up salt water fish for about 10 years. |