Sorry to be late to the party. Not up to reading the entire thread at the moment but to speak to your OP.
Firstly you must consider the fish. By that I mean there is a very dramatic difference in the results of line breeding in different animals because some fish are VERY predisposed to inbreeding and have a amazing genetic buffer to it. Certain african cichlids can inbreed and inbreed for over dozens or perhaps 100 generations with little ill effect. That proves the point that you can probably line breed those fish without loosing the WILD appearance. At most you might see an improvement or degradation of color based on the breeding habits.
Inversely as you've sighted other fish, apparently angel fish can easily go into decline rapidly from captive breeding. Now in the case of angels I would point out that their growth and fineage development is probably DRAMATICALLY effected by the tank they are raised in, the flow of the water, and other factors. you could rapidly create an unintentional situation of fish being stunted or even more dramatically "wiped out" or "allowed to live" simply by changing water flow in the tank. Take the instance of too much flow in a tank with fry, bam your longer finned offspring will suffer, stress, die and you are left with the shorter finned and more physically robust specimens. On the flip side say you only use sponge filters, you have NO current in your tank, odds are some more fintastic angels will survive than would in the wild to reach adult hood. Now you are like, WOW that is a cool angel lets breed that outlier. And there ya go, 2 generations in and you have made a huge shift. So many variables and considerations. If the preservation of the natural form is to be our goal we must be extremely perceptive to all the possibilities.
The single greatest evil to me(with regards to this topic) is hybridization and full on gene splicing. Those glow danios and flower-horns are chief offenders. I refuse to ever breed them or give a breeder business. I'm not about to buy up and cull them, that is nuts. But I won't put money in the hands for their makers.
Firstly you must consider the fish. By that I mean there is a very dramatic difference in the results of line breeding in different animals because some fish are VERY predisposed to inbreeding and have a amazing genetic buffer to it. Certain african cichlids can inbreed and inbreed for over dozens or perhaps 100 generations with little ill effect. That proves the point that you can probably line breed those fish without loosing the WILD appearance. At most you might see an improvement or degradation of color based on the breeding habits.
Inversely as you've sighted other fish, apparently angel fish can easily go into decline rapidly from captive breeding. Now in the case of angels I would point out that their growth and fineage development is probably DRAMATICALLY effected by the tank they are raised in, the flow of the water, and other factors. you could rapidly create an unintentional situation of fish being stunted or even more dramatically "wiped out" or "allowed to live" simply by changing water flow in the tank. Take the instance of too much flow in a tank with fry, bam your longer finned offspring will suffer, stress, die and you are left with the shorter finned and more physically robust specimens. On the flip side say you only use sponge filters, you have NO current in your tank, odds are some more fintastic angels will survive than would in the wild to reach adult hood. Now you are like, WOW that is a cool angel lets breed that outlier. And there ya go, 2 generations in and you have made a huge shift. So many variables and considerations. If the preservation of the natural form is to be our goal we must be extremely perceptive to all the possibilities.
The single greatest evil to me(with regards to this topic) is hybridization and full on gene splicing. Those glow danios and flower-horns are chief offenders. I refuse to ever breed them or give a breeder business. I'm not about to buy up and cull them, that is nuts. But I won't put money in the hands for their makers.