A recent question came up about stray voltage.
All information I've gathered about the subject is anecdotal, but there is a lot of it (not that that makes it right). There has been proven problems with keeping sharks and stray voltage but not clear evidence that it affects Tangs. My thought is that a grounding probe coupled with a GFCI can save your life and also happens to eliminate stray voltage in the tank.
My understanding is that stray voltage can have three sources.
1 - Magnetic coils (like a powerhead).
2 - Voltage leaks (like an insulated wire that is wearing thin).
3 - High effeciency lighting (VHO
The theory leans toward stray voltage affecting the Lateral Line on highly sensitive fish. Deep water fish have the most sensitive lateral lines followed by Sharks. Tangs also happen to have very sensitive lateral lines.
That exausts my knowledge of the subject.