Richard Sexton wrote:
Got a picture? Any chance it's this fish:

http://www.nanfa.org/articles/acgoby.shtml

Well I don't have a picture of mine but I did find some decent photos
of other candy stripe gobys when I was trying to figure out what he was
and I'm pretty sure of the identification. Take a look:
http://forum.aquariumhobbyist.com/go...ssages/60.html

Notice the red line running down the tip of both the dorsal and adipose
(I think this is the right term - correct me if I'm wrong) fins. Also
on the dorsal fin there is a second red line running through the middle
of the fin. Aside from these color traits there is also body and fin
shape which both match up exactly to what I have and the verticle
stripes along the body that I assume give the fish its name.

As for the goby you suggest it does have some similarities but also
some significant differences. Take a look at this page which includes a
photo and drawing consistent with the written description in the link
you provided:
http://www.fishbase.org/Photos/Thumb...ry.cfm?ID=3853

I'm going to use the drawing as reference since the features are more
promininent in it. Notice the dorsal fin rays that are quite
significant in this fish and not present at all in mine. Also the fin
shape in general is slightly different. The stripes are there is both
species and also the general body shape is the same. Slight color
differences are also there but since the link you provided discusses
wide variations in color I don't think that is very significant. I
would also say the head is slightly more blunt and the mouth is lower
and differently shaped.

After watching the goby interact with the cardinals this morning I
think the danger is over. He was probably just taking advantage of a
free meal. The cardinals were quite stressed when I got them back from
the LFS. I didn't realize just how badly their condition was until they
had been in my tank for a few hours and started to show their true
coloration. They are much happier now though I suspect I may loose a
few due to the bad treatment in the LFS. As long as I have at least 8
by the end of the week I'll be happy.

-Daniel