Tests on fish, which many say cannot be refrozen, showed no difference after refreezing.
Do you recall where you heard this?
I'm not questioning the validity of your statement, I'm just curious of who would feel the need to do such a test.
They'd have to be really naive of the common practices of commercially processed seafood's.
If one was to follow a nice fresh caught Alaskan salmon from the day he was first brought out of the water all the way to the the grocery shelf, they may be surprised as to how many times that fish may have been frozen and thawed and what countries it may have visited along the way.
It's possible you could buy a salmon fillet at a lower 48 grocery or seafood market that had only been frozen once prior to your purchase it but it's likely that any salmon you see at a seafood counter has been through the freeze/thaw process 2 to 3 times before you buy it and even more is possible.