I've had the blue and gold blenny and really liked it. I kept it in my nano tank and it was happy. Unfortunately I lost it to a bacterial infection brought in by another fish. I do plan to get another for my nano tank in the future.
I see you have a 90g tank and just want to point out that the blue and gold is a small blenny. I have a large (2.5+") tailspot blenny in my 90g and it still gets lost in the shuffle sometimes. If I were going to put a blenny in a 90g I think I'd go with a larger blenny like a midas blenny, starry blenny, or super red ember blenny. Don't get me wrong, I absolutely love my tailspot, but most smaller blennies aren't anywhere near as large as mine and would otherwise get totally lost or out-competed by the other fish. Hope this helps!