Fran Legman has shared her 2 Liter Bottle Fish:
(page may take a while to load - lots of images)
She got this idea from the NJAE Conference.
Bottles are cut to shape the fish - designs drawn with
Permanent markers on the outside - then colored on the
inside with gel markers. The tails are stapled
If you have a torch - you can shape the bottle opening
to make a mouth (link was shared on Getty list showing
this - but I didn't save it).