I always thought raw fish was filled with parasites and worms, which was why ‘raw’ fish is always flash frozen first. I’d imagine in a situation where the chances of dehydration are so high, risking food poisoning would be life or death.
I believe they manage this because they have a monopoly on the world’s supply, and they only ‘loan’ them to zoos on the condition that they still belong to China (including any offspring).
Tom Scott would be my top pick for quality YouTube not tied to a specific hobby. His videos are great.