Lieutenant Tang, parasitic skin patches?

[Vicki]

My new Lieutenant tang has developed brown speckled patches over his body. He was only I the tank about a week. After about 2 days I finally managed to catch him and he is now in a quarantine tank dosed with copper. That was about 2 days ago and it seems to have spread more across his body, but he is eating. Should I be doing anything else and should I be worried about the other fish in the first tank?

Nitrates and Nitrites negligible, usually zero or hardly detectable. Calcium maintained at about 440, kH (alkalinity) at about = 8, ammonia between zero and 0.6 tops, Salinity 0.24, Magnesium around 1200 to 1280, pH 8.3, Phosphates = 0, Temp 25
In the tank I have built up over the last few months:
3 clowns
1 bi coloured Blennie
1 Purple tang
1 Blue tang
1 Yellow tang
1 Lieutenant tang
2 Golden headed Gobbies
1 Pixie Hawkfish
1 Royal Dotty
1 Foxface
1 Flame Angel
1 Harlequin tusk

These fish are all small (except the lieutenant tang).
I have a dozen or so frags (mostly polyps) and 2 anemones.

I feed them a pinch of flakes in the morning and about 1 tsp in the evening of chopped fresh mussel or frozen marine foods.

I have recently had a brown algae problem which I seem to have got under control by turning the lights off for 2 days and then down to 7 hrs a day.

 

[melosu58]

One thing about tangs is that they are herbivores. Are you feeding them any greens like dried seaweed or spirulina. That seems like a pretty big bioload in such a quick time. I would suggest you are at your limit if you have not already passed it.

 

[Vicki]

I'm feeding Nori on a veggie clip.