I recently added my first fish (blue damsel) to my tank and it died in two days. I have a newly cycled 120 gallon saltwater tank. I have had it up and running for about 8 weeks. I used ammonia to get my cycle started. My tank went through the normal cycle and both ammonia and nitrites dropped to zero. I added 3 small blue legged hermit crabs about a week and a half ago. I added 2 small emerald crabs and a chocolate starfish at the same time I added the damsel. The fish looked very healthy and it swam back and forth along the back wall. This morning it was dead. The LFS
did mention that they had a problem with their tanks losing power the week before.
Nitrates 15 - 20 ppm
about 4 days ago
I don't want to add any more fish until I do some more checking. Is there anything else I should be checking for? I have had freshwater tanks in the past and I don't ever remember having any trouble keeping the fish alive.