I tried to model it after an actual bluefin tuna, but with a pink fin on top because I didn't have yellow felt. To make the lines on the fin, I just used thread, and to mimic the yellow on the other fin, I bedazzled him with sequins :) Also, instead of googly eyes, I heeded someone else's suggestion and painted it on.
I had to cut the sushi off the first time and sew it back on because with new green because the original wasn't tall enough to fit all of the fish. I had underestimated the height loss due to the stitching on both sides of the sushi rice, and the extra bulk of the fish due to the details. Very durable because of all the extra stitching, which helped the felt not stretch too much, but it's still flexible enough to flip inside out without a big struggle.
With felt being only 34 cents a sheet, this entire project was less than my morning coffee! The extra time it took to stitch (while I was watching tv) gave me something fun to do for the day.