Thank you both.
Fishdance, I am at awe at your experience and knowledge. So cool to have here members like you. We appreciate you, your time and advice very much.
I think though that knowingly or not you have avoided answering two of the main questions posed above.
I am sure you have other priorities than to engage in an exchange where you may not learn anything... so no expectations.
...
FD: Why do they hybridize or sterilize fish fertility or create single sex fish? There are multiple reasons but as this costs time, effort and money you can be sure it is worth the effort or it wouldn't happen.
TBTB: First, this is not a pro argument but could be readily viewed as a circular argument. Second, the hybridization and sterilization must not be lumped, because the latter is agreed upon between us while the former is not at all. Also, list, please, the multiple reasons, if you will.
FD: Yes hybrid vigor is definitely advantagous but limited to the first filial (F1) so you need to return to the original species breeding to maintain benefits.
TBTB: Perhaps (and most likely) we get culled, underperforming hybrid fish, refuse, dinks, runts, and often obviously deformed junk, gene hiccups in our ornamental fish trade but I've not noted any notable advantage in the growth rate and carcass yield in say half a dozen TSNxRTC I raised from little to adults versus the parents. I agree my experience is of no or poor guidance and is utterly anti-scientific, but that's all I got to go by for the time being.
FD: The difficult thing for most hobbysit fish keepers to comprehend is that "pure species " is a man made artificial definition / classification.
TBTB: To me this is the case of baby and the bath water. I don't think anyone of us has a problem telling a petri dish, man-made species from genuine or natural or non-man-made. It is clear as day.
FD: And equally hard to understand is that a solid belief system may need to be discarded before new ideas start to make sense.
TBTB: Yes. It's a double edged sword that works for both good things and bad things, hence, not an argument pro or con. Just a for instance. Perhaps a poor example but... Do you know how the USA started its first actual nuclear bomb detonation test? Many scientists warned them that the consequences are unpredictable and that there was a chance the Pentagon might start an irreversible nuclear reaction that will fry the whole planet.
FD: I'm sure there are real dangers with clone, genetic modification, etc.
TBTB: So we agree on something. I am glad.
FD: Just as there are real dangers of trying to keep a snapshot of a fish that continues to evolve and change in the wild.
TBTB: And what exactly these dangers are? My thoughts may sound stupid or inapplicable, depending on what exactly you are saying, but the thought that's occurring to me is that animals evolve over millions of years. What does this have to do with the subject matter?n Also, what's preventing a breeder from utilizing the latest and the greatest wild specimen to replace or renew their gene pool?
FD: Late last year, I assisted a fish farm in Asia to produce well over 300,000 baby datnoides from one spawn. I'm sure this could be done "naturally" in an artificial environment one day but right now, it's better to have these fish available this way than to have fishermen netting them out of the wild.
TBTB: That's most commendable by my book but again we are talking a genuine species production for the justifiable needs of humankind, which I personally have no moral / ethical problem with.