Help with sick blackcap basslet

[yeldarbj]

I've had this basslet for 2 weeks. He was very healthy when added to the tank, then was fiercely picked on by a 6-line wrasse, just fin damage. The wrasse was removed, the basslet had been healing great although it looked like he may have had a couple spots of ich perhaps due to the stress, although they only lasted for about 2 days and none reappeared (may not have been ich after all). The basslet has always been an active eater all the time (with and without garlic extreme added to a variety of frozen foods) until yesterday when it wouldn't eat at all, just stayed in its normal hangout in the rock, although he looked fine.
This morning, the basslet has moved to a very small, protected cave in the rock and is breathing heavily. He has some white/grey lesions behind his gills and next to his fins, plus some spotting along its back (which could be some ich, but looks more like debris clinging to the fish from the rocks). I attached the best pic that I could get.
I lost a new fairy wrasse to some sort of fin rot last week (finally died in a qt tank while getting treated), but the blackcap has looked great until today.
Do I just need to get him out of the tank and treat him too? I'm guessing it is bacterial. I have some nitrofurazone that the lfs recommended (didn't work with the wrasse, though it may have been too late).
My water parameters are fine - 0 ammonia/nitrite/nitrate, ph is low this morning 7.8 but usually rises to 8.1 or 8.2 by afternoon. Other fish in the tank appear fine - false perc., small foxface, very small mandarin.
Any help is appreciated. Thanks.

 

[yeldarbj]

My blackcap didn't even make it through the day.
Any ideas??? I'm just stunned that he went from looking and eating great on Sunday to dead by 1:00 pm today. Like I posted he didn't want to eat yesterday and showed first signs of suffering this morning. What could take him out so fast? The other fish appear fine.

 

[beth]

Hard to really tell what that is with the blurry picture. Since you lost another fish, maybe you should give some info on your tank, what is in it, size, and water readings.

 

[yeldarbj]

My tank is a 65 gallon, with about 100 lbs of rock, and varied cleanup crew - snails, peppermint shrimp, scarlet reef hermits, starfish, emerald crab, porcelain crabs. I previously had a six-line wrasse, false percula clown, and small mandarin. My water parameters have been very consistent, temp is 80, 0 ammonia, 0 nitrite, 0 nitrate, 0 phosphates, ph generally 8.1 (usually tested late in the day, I noticed this morning that it dips to 7.8 in the morning).
Two weeks ago, I added a small blackcap basslet, a small fairy wrasse, and a tiny watchman goby. Thesixline was immediately aggressive toward the basslet and to a lesser extent the wrasse. I traded in the sixline for a jeuvenile foxface. The basslet and fairy wrasse are now dead.