User blog comment:Jamintheinfinite/Subnautica Creature Evolution/@comment-35546951-20181012164522/@comment-28450065-20181012192257

It says that the creature was "eel-like in structure". That does not make it a relative of the eels living today.

The electric EEL from Earth is not even an eel yet is also eel-like in structure.

For further proof of this within the game, look at the Crabsnake. It is definitely eel-like in structure, but there is no mention of a relation to the other eels.