White film on maroon clown

So these two fish have been in qt for almost six weeks. I've started TTM two days ago. (Backwards yes but this is how it worked out). They've been doing great and eating fine all this time. I dosed prazipro in the qt and observed nothing on them at any point and time. I look today and it appears the smaller on has a milky white substance on the top of its head. It's not stringy and is shaped like a T. It goes down towards its head and then down the body. Fish ate a little. Temp 76, sg 1.025, ph 8.2 in the Bucket.