red scooter blenny is a lot like a mandarin, they feast on copepods, constantly. they're known to wipe out a tanks population, then starve to death.
for a 12G tank unless you're gonna supplement pods
or spend the quality time training on frozen foods (which might be a failed attempt) i'd suggest against it.
i tried to ask on here if i could keep a mandarin or scooter blenny in my 14G biocube and was talked out of it, as stubborn as i was =]
so yeah unless you're gonna buy copepods or attatch a rather large refugium to your tank i'd advise against it
=/ sorry you're getting shot down, maybe a firefish goby? mine has lots of personality