Since a few people asked after my last post, here's how I did it. The trick to getting a fish head to look right is a stiff base layer under the pretty fabric. I cut two side panels and a gusset from heavyweight canvas, basted that shell together first, and only then did I fit the outer fabric over it. Skipping that step is how you get a sad deflated sock instead of a proud fish.
For the shape, less is more. My first attempt had a snout like a shovel because I curved the side seams too aggressively. Round it off gently and stuff the nose area firmly with polyester filling so it stands up on its own. The eye is just a circle of felt backed with fusible web, pressed on and then hand stitched around the edge so it doesn't peel. The fin on top needs a wire or pipe cleaner inside the seam allowance, otherwise it flops the second you put it on. And finish the bottom edge with bias binding before you attach any trim, because trying to bind around dangling beads is misery. Do the beading last, always. Took me three weekends total. Worth every pin.