These rays are deformed and should be culled. There is no argument. They are as undesirable as a 3 legged puppy to a pedigree dog breeder. Seeking commerce from them only demonstrates how ridiculous the ornamental fish trade sometimes gets and how utterly without an idea so many people are that would spend more money on a ray that should be culled than on a healthy ray from the same species.
These deformities could be caused by many different things such as over or under feeding, especially fatty food , the bioavailability of proteins and amino acids, pollution such as pesticides or heavy metals, Ultraviolet B, some parasites and many more possibilities.
This occurs also in the wild but a ray with deformity is normally quickly food for predators.
Genetics/inbreeding is almost certainly not the cause in the majority of cases.
The best prevention is varied balanced diet, ultra clean water and responsible husbandry