Most colors are easier to fix than form. But you are working with a very difficult color combo :
Dragons are suppose to have white body and colored fins - which names the dragon color. But this is almost impossible for irid colors. For some reason their bodies will be irid colors too. So a green dragon would have green body and fin, so will blue and steel blue dragons.
You are working with a white body with royal blue fins . . . what I call "a true blue dragon" because it is in accordance to the original dragon "setup". This is very hard to achieve - but easily lost.
I say work for that color. Once you have a good number of them, begin cross breeding to other dragon colors to fix the fin form. . . . with this color, your goal would be totally white body with totally blue fins. . . . it wont be easy, but then again too easy wouldn't make it interesting, would it. :)