Missing

One of my firefish has gone missing. I haven't seen it for just about a week now. I've peered into its bolt hole but have not been able to spot it. So, like Steve Fossett, I'll just have to declare it dead at this point.

This is the second mystery death in my tank since it has been well established. First a clown fish, now a firefish. What killed them I may never know. I do know that my water quality is close to perfect. Nitrates at 5 ppm, phosphate 0, calcium 460 ppm, pH 8.3. In both cases the fish looked perfectly healthy the day before.

My blue tang has looked better also. It developed some white spots around the fin on its left side. It looks like it is recovering but this is of some concern. I know that the water quality is good so what else can I do?