There was alot of selective breeding involved to get that fh to look the way it does. So any breeding outside of the strain will add traits back in and also decrease your odds of hitting those traits the fh carries. Pretty much adding extra cards and shuffling the deck if you know what I mean. Especially crossing to a pure breed.
You may get a few cool fish but lots will be pretty bland. You can't keep them all and it probably isn't easy getting rid of unattractive fish so cull heavily.
