Fish – Differences between haddock and cod

Assuming the cod was the same quality as before and you de-salted the fish in the fridge for 24 to 48 hours, then I would also guess overcooking. Rendering the gelatin at 45°C (as suggested in the paper @yossarian uncovered) should prevent the fish from cooking and give enough time to get it into the oil. You can always cook the fish in a separate step after you made the pil pil.

Modern techniques for salting cod use less salt and create a product that will not be edible by future archeologists, so store in a dry cool place (tightly wrapped in the fridge).

I have had this problem and thought it was the taste of tin-foil that I used to rolled up and put into the belly of the fish to stand it up in the oven. So, I was very interested to hear an interviewer on the radio 3RRR in melbourne, talking to a chef who mentioned fish, like Snapper, are susceptible to that metalic taste if they are caught and die too slowly. The slower they take to die, the more stress the fish goes through and the stress hormone accumulates in the flesh particularly around the belly. I think they said a pinker snapper is better than a pale one for taste.