I don't believe it was your batter. A fishy odor and flavor, especially since it was getting stronger, signals a spoiled calamari. Good, fresh calamari should have nearly no smell except a light smell of the ocean - in a good way. It may not even be your grocer's fault since they probably got it in frozen. If any frozen seafood should thaw and then refreeze, it's gone... no good... bye, bye. And is what may have happened to yours somewhere en-route from the sea to your stove.
And it's really not all that uncommon, unfortunately.
"Food is our common ground, a universal experience." - James Beard