Martin Thoene wrote:identification of healthy specimen cannot be done reliably either, regardless of the level of intellegence.
Nothing is 100% reliable but it doesn't take intelligence to identify good fish, just careful observation.
It is not the case. I've seen many cases where there are no warning signs at all, and the fish carries a deadly disease nonetheless.
I can look at your photos and see bad fish straight away in many cases
Next time you do, please take a moment to say so. It is quite possible that you know some factors I don't.
If you wish to purchase unhealthy fish and attempt to become knowledgeable about what it takes to turn them around by experimentation that's your choice. It would appear statistically though that you are very often unsuccessful and you might enjoy the hobby more if you weren't continually living in the angst of it all.
I do. Not much angst for as long as the fish is in a qtank, and the success rate has been steadily improving. There is no way to improve the skills other than experimenting and occasionally failing. And there is no way to experiment other than by buying sick animals once in a while.
I chose to take a chance on this loach since I'm interested in watching how it develops, do you see something wrong with it?
I see nothing wrong in choosing an unusually marked fish to see how it develops......did it myself recently with an unusual Yoyo......but getting one with a highly visible tumour/cyst/deformity is not something I would choose. Or was this factor missed in your initial enthusiasm?
The factor was missed. The growth was
not highly visible, it is <1mm and is located on a white stripe, the fish is very small, and the store light was not strong enough. This makes no difference, I'd have taken it anyway, and I still can replace/return it at any time -- not doing this.