BLACKENING
blackening: translation
1) a black discolouration of canned fish caused by defects in the lining of the can such that sulphides in the flesh interact with the can steel to from black iron sulphide
2) black discolouration in Molva dypterigia caused by the ink bag parasite, a copepod (Sarcotaces arcticus), which has an ink bag that may be perforated during filleting. The parasite can be cut out of the fish without staining the surrounding flesh