it happpens out of my 15 that were saved 3 of them have crooked spine it could be something like in breeding of guppies of just unlucky. apparently it shortens their life and ive been told they dont live long but mine are still alive after 3 months and seem perfectly fine
deformed fish most of the time that have a bent spine will struggles to feed, and if there isnt enough oxygen on the water they find it hard to surface, so suffer a slow lingering death, sometimes if they are having trouble breeding and there going to suffer its best to euthanize them