Fish dying..... one at a time

[Methamphetareef]

Hi,
I have a 150 gallon reef tank approximately 8 months old. Water quality is good; PH 8.3, salinity 1.024, Dkh 9.0, Calcium 400 ppm, Ammonia 0, Nitrite 0, Nitrate <10 ppm. Inverts (coral, long tentacle anemone, snails, crabs, etc) are doing excellent. Approximately 3 weeks ago I started losing a fish every couple of days. Among the deceased are; yellow tang, lawnmower blennie, firefish, jawfish. ALL of these fish were doing well and in the tank for at least 2 months. Also, each fish died one at a time. I originally thought I may have a mantis shrimp because I had bought a large piece of live rock prior to the fish dying. But I have found several of the fish and can not see any apparent wounds. I have witnessed several of the deceased swimming erratically prior to death. As I said all deaths happen one at a time with the other tank mates eating and doing fine. Any ideas? Is something “stinging� them? Any help would be GREATLY appreciated

[Blindmelonbob]

Have you checked for stray voltage? That seems to be a common recommendation at least.