I think the theme on this website might be patented. Try googling CSS codes for a fish theme. Or, are you asking how to make custom CSS coding for a fish theme?

@Mr_Grimm : Sort of how to make my own. I mean, I think that it’s technically a cursor-follower?

I find it terribly distracting. My eyes keep getting dragged away from the content. But I think it must be coming from this embedded object:

It appears to ba a background image. I imagine it is Flash and not an animated GIF because a GIF that large would be a huge file size. The background parameters are spelled out in the CSS for the BODY element. But there is no background-image specified. So I presume it’s being put in by a script that isn’t visible as I view the site’s HTML source. It’s a puzzle.

OK, checking back, I thought to right click and select View Background in FF. The background is a whole separate page, which is why we weren’t seeing it in the source code of the landing page. It appears to be a Flash mouse follower as you suspected.