In comments of this video (
https://www.youtube.com/watch?v=TgW1Kgdya0A) he said all of his fish are dead due to velvet and he started a new project. I am not sure if cartilaginous fish can even get velvet. They most likely died due to lack of space and resulting stress. Considering the cost of those fish and restocking such a tank, he is simply a rich p-r-i-c-k (sorry but I want this to be visible) who doesnt care about animals.