Leptecodon (meaning "small tooth") is a genus of prehistoric ray-finned fish which was described by Williston in 1899 and was possibly preyed on by other sea creatures.

This fish sometimes hid in clams such as Inoceramus.

The first-discovered fossil was inside a clam.

Many believe that Leptecodon had formed a symbiotic relationship with the clam rather than get eaten by Inoceramus.

Another fish from the same time and place, Caproberyx, has also been found among Inoceramus.