Here's another of my blenny. Interestingly, when I got him he was jet black, and after a couple weeks of mowing down the hair algae in my tank, he's faded to a yellowish/greenish/grey color. He's still cool!!
John - I have one of these also I think they are Atrosalarias fuscus maybe? Black sailfin blennies - mine also has seemed to change colors over past month or two but is VERY hard to get a pic of especially the whole body and his awesome plumage.
It looks like he's swallowed a croaker marble. Kelly thinks he's...'plugged' because he's got such a huge belly. But he just keeps on happily eating everything in sight! hehe
I've got an old abalone shell in the tank and he likes to hang out up under the lip of it. He also sits in a hole in a rock right under the edge of the big anemone.