I don't believe rav belsky considers the pesak of gedoley haposkim in EY as "binding halach". So for him he is not trumping " halach". It never is...
Back to the fish, I suggest you actually read some of these kuntrisim, you will find that there is very little debate about the facts.
There are questions how to how to interpret these facts, and obviously machlokesim in halacha.
The gedoley haposkim all asser, and to dismiss them as "uninformed" on a sheila that has been debated and discussed extensively throughout the world, is very wrong.
I just saw this discussion. Not only have I read all the kuntraissim with all the back and forth bashing, I also spent a lot of time on those se'ifim in so man 84, the psak lehaiteira is pretty straight forward on the other hand the the psak lechumra is left with several options.
1. Chazal made a mistake in the concept of spontaneous generation and therefore the worms in the flesh were always assur (this is the approach that R' Tendler takes which is quite unpopular as one can imagine.
2. Nishtana hateva . The worms that chazal were matir are not the Anasakis that we find to day (how can one prove nishtana hateva?
3. Some sort of Safek issur based on the above
4. They're muttar and the geder of chazal's understanding of minei gadli, was as it appeared to the eye with external scientific knowledge .