Yes, hybrid marine angels have been caught and they command very high price due to rarity. Coral reefs are biological islands that promote speciation. But in rare occasions, fish from one island are blown over to another island in storm events creating opportunity for hybridization. Natural hybridization of FW fish have also occurred and witnessed by fish collectors, often caused by human activities such as canal construction.
Yes, artificial hybridization of ornamental fish receives a lot of criticism, specially among cichlid keepers. Not much is said about inbreeding pure gene though that can lead to poor health and short life, as witnessed by pure breed dog and fancy goldfish. Whereas wild looking koi can live over 100 years, pure breed fancy goldfish only live a few years. The longest living animal on record is a koi in a Japanese temple that lived to 226 years. Many of our aquacultured food fish such as stripe bass and tilapia are hybrids because they are more hardy, so are many of our crops and domesticated animal.
Only recently that coral fish are bred and cultured successfully in scale. It's amazing that all crown fish are born male, only the dominant one changes sex later to breeding female, so are groupers and other marine fish. FW fish have been known to change sex too, but it is an anomaly rather than a natural progression. There is a lot we don't know about marine fish as breeding them in captive environment is nearly impossible.