My wrasse has died

[coral8]

I just had a pretty rough morning, found my six-line wrasse dead after only a week. I had a bad feeling last night, he just didn't look right and wasn't acting himself. I mean, his poop was white and stringy, that's always a bad sign, especially during feeding time when he's usually all over the food. His mouth was wide open, and he was just swimming against the powerhead current in one spot, not hunting for bugs like he normally does. Then right before the lights went out, he just settled down between two small pieces of LR and wouldn't move, that's when I knew it was probably over for him.

Even if I knew what was wrong, it was too late to do anything about it by the time I noticed. It's weird, he was fine that morning. Does anyone have any idea what could've happened? I've tested all my levels, and they're perfect, the other fish are fine, and so is the conch. I'm planning on getting another one soon, so I'd love to know what happened to this one.

[fleeton]

Honestly, I'm stumped, but internal parasite or Cyanide poisoning from capture are the only two things that come to mind.