flashing, itching blenny
I have a 3 inch lawnmower blenny in a 55 gallon tank with one other fish, a Clarke's anemonefish. An Elbii angelfish was with them, but died yesterday of (I think) bacterial and fungal infection. All water parameters are perfect(no ammonia, virtually no nitrites and very low nitrates) except pH which was down to 8.0 after a 25% water change and the temperature, which was up to %80. Both have been corrected with buffering powder and lowering the thermostat.
The angelfish died of a two week illnesss that started with a cloudy eye, progressed to ragged fins and two cloudy eyes, and eventually listlessness and rapid breathing. It responded to Sulfa drugs and Melafix and was almost cured before quickly relapsing. At one point it has white salt specks (like Ich), which disappeared with a freshwater dip and treatment. I think this must have been a case of one underlying problem weakening the fish and leading to secondary infections. I'm still not sure which is which.
The blenny has no visible problems or spots, and is eating well and vigourously. He hasn't had contact with the angelfish since it began sulfa treatment in the hospital tank. Melafix was used in the main aquarium. The blenny has been in the tank for months and has had no problem. The angel was a new acquisition. The anemonefish is unaffected
The blenny appears to be striking himself sideways against the gravel and rocks, as if he wanted to knock something off his skin. He sits normally for a while and then hurls himself against the rocks or sand. He seems fine afterward. I can't see anything on him. Could this be related to the angelfish's death? What should I do? I don't want to put him in the infected quarantine tank.
Thank you for your help.