Scientists remain baffled.
Here's a possible clue. None of the fish in the tins had heads or tails. Whatever toxin attacked them destroyed their heads and tails.
Also time to file suit against the makers of the tins. Something in the metal killed the poor, helpless sardines, who were often subjected to hatred by the other fish just becuase they were different. They were just starting to turn their little lives around.
Something smells fishy about all this.