Hi,
In my LFS I saw a blue Aphasia. I didn't know what it was so I asked. It was a stinger and a bad thing, pretty or not.
I had never seen blue, and I mean blue like hippo tang blue, so brown and ugly is not a good way to decide if it is aphasia.
Your picture sure looks like aphasia to me. 4 of them in a single tank doesn't sound like a cup coral hitchhiker. JMO