Line breeding is an artificial selection process to enhance certain desirable traits. There is no constraint that line breeding must be from pure species. Some are line bred hybrids, which include fancy livebearers, FH, and most "red" peacock.
Hybrids can be ool, this is a good example, blood parrots are bad example.
I'd love to have some wacky combo, I don't even know if it's possible, of a jagxcon or red devilxcon.
Honestly I understand where people dislike hybrids but All pets are bred into different forms or another and fish really aren't too different. I know that they are seperate species but many types of birds have been hybridized and various canid and feline hybrids exist.
The way I see it unless you are spreading the fry without telling people they are hybrids whats the problem? If you breed a hybrid and people are interested in it then nobody is losing out. Also think of the scientific value, I don`t think any of us here have ever known of a Nic and Jag hybridizing.
Jag x Con hybrid.