The black cod is a saltwater cod found in the frigid ocean at the northern end of Pegankapan island. It can be caught off of the ferry using large baits. In real life, this fish is not near as big as in the game. This fish can grow to about 7-8 pounds, and can grow to about 2 feet. This fish is part of the Nototheniidae. The people who created this game are probably attributing this name to the sablefish, also known as the black cod, which can grow to 3 feet, but not a real cod. Both of these fish live in Sub-Antarctic, so they have antifreeze proteins in their blood so that their blood doesn't freeze.
Bait and Tackle:
Quick Hitter (Large)
This fish is not rare, but not common. This fish can be caught most easily with 3 star L-XL rod/reel, and Quick Hitter or Rainbow (Large)