I was young when I saw this movie or TV movie. It would have been in the early to mid 70’s. I remember young children being the stars. A vague memory of a boy and the eel was his friend.
He swam under a boat dock or a bridge looking for something and came upon an moray eel. I remember him not being afraid of the eel which seemed strange to me. I also remember it being strange that he spent so much time under water.
The movie was not “The Giant Eel”. The child(ren) spoke English.