China consumes 65 millions tons of fish a year. So 200k ton is not much. This could just be a trial, and they can build more. Considering how much fish depletion is a huge problem overall globally, they can probably build 100 more once the first ships are considered a success.
The biggest problem is some fish like salmon or tuna have high needs for migration, so won't work for these ships. But fish like tilapia or snapper probably can work and reduce mercury content in the fish.