The ezochius maris is found in some medieval encyclopedias. Its identity is unknown. It is said to be a very large fish with 42 teeth in its lower jaw and none in its upper jaw. The upper jaw has 42 holes into which the lower teeth fit when the jaws are closed. It has an eye four cubits wide, and more intestines than are found in 40 oxen.

Thomas of Cantimpré has an account of another fish called ezochius (flying fish), but the description is entirely different. Where Thomas got his information is unknown.