Jigs,
what I use for all my fish painting are automotive lacquers. you can get just about anything you want for paint, and most are semitransparent metalics. you will need lacquer thinner when using it.
you would be able to fine most acrylic paints at a hobby or craft stores, they are water soluable and are much easier to paint with, or to learn to use an airbrush.
good luck.
Jack.