In Christian folklore the haddock fish is associated with St. Peter. This is largely due to the two black marks near it’s gills. The marks were said to have been caused by St. Peter when he took the tribute money from it’s mouth.
The haddock is also considered to be the Lord’s fish. It was said that the marks were created when the Lord held the fish in order to make enough fish to feed the multitudes. This is a fairly common folk belief in the British Isles.
In old New England the superstition held that the fish got it’ marks when the devil tried to grasp the fish. The two black lines were the burn marks resulting from the fish slipping from the old devils grip.
In Scotland it was believed to be unlucky to burn the bones of a haddock.If a fisher were to make the bad choice of burning fish bones he would find himself a stranger in any home.
Fish are frequently used as a Christian symbol with Christ being the fisher of men. As I had just mentioned Christ miraculously feed the multitude with five loafs of bread and two fish. The Greek word for fish is ichothos.