Help with diagnosis - red blotches

[Jagermeister]

I have a yellow coris wrasse who has been in qt for 4 days now with another coris wrasse and a starry blenny. The wrasses have been swimming around every day and eating well. Then today, I found one of the coris wrasses laying on his side and having difficulty swimming.

Ammonia and nitrate in the qt are zero. The qt has been running for over a year and has sand in it because I've qt'd a lot of delicate wrasses who like to bury themselves.

The wrasse has red lined blotches on his body. It looks like blood under the skin and there's color loss. This all appeared over night and is on both sides of the body.

Here's a couple pics

From my research I'm thinking this may be a bacterial infection? What's the best way to treat? Marycyn 2?

Thanks for any help. I don't think he has much long to go.

 

[Jagermeister]

So, the wrasse pictured died yesterday evening. This morning, the second yellow coris wrasse is laying on his side, breathing hard, with the same reddish lesions all over it's body.

There's also a starry blenny and cleaner wrasse in the qt who seem unaffected so far.

Anyone have any ideas? I added a dose of Melafix to the qt yesterday. Obviously didn't help.