Macchanu

[1][2][3][4][5] As per these versions of Ramayana, during one of the battles with Ravana's army, Hanuman encounters one powerful opponent, who looked like vanara from waist-up but had tail of a fish.

After a fierce battle, as Hanuman was about to hit the creature with his weapons, a golden star shining in the sky above, reveals by way of aakashwani that the enemy, whom he is going to harm is his own son born by his union with Sovann Maccha, the mermaid daughter of Ravana.

Macchanu introduces himself as son of Hanuman and Sovann Maccha and so they finally identify and embrace each other.

He tells Hanuman that Maiyarab is his foster father, who had picked him up lying on sea shore, where his mother had left him.

Although, he does not want to betray Maiyarab but tells Hanuman through a riddle the entrance to the netherworld lies inside the lotus in the pond he was guarding.