Predator, you should consider clearing between sections of your painting process.
For example, when you get your base colors faded on and before you start adding stripes or scales, shoot some clear first. Or you can even use Krylon spray can clear. I like automotive clear because its tough, hard, and I can shoot it with my airbrush.
That way if you make a mistake with the scales, stripes, gills, fins or any other detail work, you can usually just wipe if off and start over without ruining the fades of base colors underneath. It can prevent you from having to re-prime and start all over again.
It can be a good idea to clear the entire job when your done. That way, the paint is good and protected while you finish the process by adding envirotex or Devcon 2 ton epoxy or whatever you choose for a finish clearcoat. Paint can be a bit delicate to handle until you get that final hard clearcoat on.