Quite frankly, I was surprised that I couldn't find a Darwin fish on Thingiverse. Or maybe I didn't look hard enough. But here it is. I've included the source file if you need to break off the feet. Also, I recommend printing this in PLA, as it will quickly melt during the second coming.

Also, I made the file a little too small, so I scaled the stl file by 150%. I think it would look better if it were even larger.

Print, affix with double-sided tape.