If it's electricity in the water, you'll see it soon with the HLLE that will rather quickly develop. However, the darting around the tank like a crackhead thing is pretty normal for a tang
Especially the sailfin...they're jumpy. (they don't stress out as badly as most tangs do, but they're a bit crazy lol) That's why they need such big tanks (135 or so since they get 16" long. Sorry, had to nag, I'm a tangs' rights' activist
)