You're on to something, keep at it!
Going with Blender first might not be the easiest way to get started... apart that Blender is free though...
Blender is very versatile but the UI is not very intuitive at first. I personally keep Blender for rendering only so far; I play with it in my spare time.
How did you get to this fish shape so far; sub-D or from loft curves or else?
Check out MoI
. It is NURBS based, it is a very friendly environment. It is still under BETA testing and you should (might) get a copy for free until it's official release... MoI beta is as stable as Vectric's VCP beta; which mean that when it come to finding bugs, it is pretty boring...
Silo is my #1 choice for sub-D. Here's one of my very first "serious" model with Silo (unfinished; no pelvic fins...).