Raw fish pieces have stuck to each other in freezer. How to take out few pieces of fish without disturbing other pieces?
The only best option is complete thaw to get them in good shape and in one piece, but that is not an option for you.

Next one up is the quick and sloppy method. But it will distroy the shape of the fish, hence the name.

My tip: Wrap the pieces of fish in a cling film/kitchen foil individually next time before freezing. That will most certainly allow you to take a few pieces out without thawing or using knife/wedge etc.