I came across this idea over at Homespun With Love and knew I had to try it! Click on the link to see her instructions. Basically you buy a bleach pen and a dark colored T-shirt. Put wax paper inside the shirt so the bleach doesn't penetrate the other side. I'm good at drawing free hand so I just Googled fish coloring pages etc. and picked one I liked.
I used the bleach pen to draw it on the t-shirt. You'll see it start to develop within a matter of mins. I didn't wait for mine to dry b/c I could see that the bleach was going to spread out more than I wanted.
Use a Q-tip to take off the access bleach.
Trace along the lines of your picture with the Q-tip and let set until you are pleased with how the bleach has developed.
Then hand wash with laundry detergent in the sink and rinse well.