help powder blue sick or hurt?

I have had him 3 weeks not and he has been getting purple sea weed and nori every day. he also eats emerald entree frozen multi pack. all my levels are fine. 1.024 sal, 0 nitrates or nitrites, normal alk, 420 calc, ph 8.4. he does have a yelow tang pestering him though. he seams stressed and swimming around in small circles vigorously.

is this bruising or a disease, or malnutrition.

 

it looks like a bbruise on his side and it has a slight brownish look.

 

Dude, do you have a QT? The first thing I think of when I hear of sick tangs is ich.

 

ick is white or black spots. all he has is a big bruised looking area on one side that happened over night. i am looking at getting a 20g long rubbermaid prolly as a quarantine tank. but i need to identify the problem asap

 

I suggest getting a 10gallon tank to put him in for now. Use the water from your tank and use a new or used filter with some bio load from your tank (used filter floss, bioballs, ect.) so it doesn't cycle. Then after a week or so, when your PB is looking better, put him in your main tank and take the yellow tang out for a couple of days. You want the weaker fish (your pb) to gain dominance in the territory. Then you can reintroduce the yellow tang and all should be well at least for a while. This doesn't always work but I've seen it do miracles.

 

How big is the tank?

 

That's a good question.