Can't say I like either...sorry but just being honest.
I too think you should just go novelty and for the inner fish geekdom.
How about my favorite avatar. "don't drink the water, fish have
SEX in it!"
Or how about a picture of some amazing expensive coral and a price tag hanging of it that says $20. Then on top of the shirt it can say "if my wife is reading this...."
Or make a hitler shirt with one of the funny sayings from this video
http://www.youtube.com/watch?v=rrOjKpSZ8PI
How about "Hitler has red bugs" and then you can have some frags on the other side with titles form the video such as "The Master Race Tort" and "Hitlers Purple Monster"