Here's a new drawing, this time of a baby zebrafish

Feel free to use this image, though please credit Lizzy Griffiths if you do :)

This one has a bit more detail, with semi-transparent pattern overlays, and a few different brush types. I also finally learnt how to use the gradient mesh tool, which I can't believe I didn't discover earlier!

...And here's a slightly younger version (~5dpf)

A tutorial on drawing a relatively realistic fish in Adobe Illustrator

If you'd rather not draw a zebrafish yourself then you're welcome to use the image I've drawn (below). Just be sure to credit Lizzy Griffiths if you do!