i wouldnt agree with doing this in just a home type setting but for commercial breeding purposes i dont see the harm, its not causing any pain at all to the fish and allows the female to get away easier, it never says what size tank he is keeping these fish in so no one can really say oh hes just doing this so he can keep them in too small a tank, he very well could have them in a good size tank but even in large tanks, fatalities with these guys will still occur when a huge male decides he wants to put the beat down on his girl. and hes not talking about totally mutilating the fin just poking a small hole in it so its not as water dynamic. fish do worse damage to themselves than this just swimming around in our tanks if they hit the decor wrong. as for answering the question of whether i would buy fish from someone who did this... yes, yes i would. like i said before this process does not cause any pain at all to the fish and prevents the death of another fish. Its not comparable whatsoever to something horrible like the companies dying fish purely for cosmetic reasons and causing these fish so much pain and stress that the majority of them die and the ones that do survive still arent able to live full lives