Fish of Darkness was a Mysterious Being from Road to Hero.
Appearance
Personality
Not much is known about it.
History
He got beat up by Saitama for an award.
Abilities & Powers
Physical Abilities
Enhanced Speed: Fish of Darkness is fairly fast.
Equipment
Whip: Fish of Darkness uses a whip. He is fairly skilled with it as he was able to give Saitama a hard time, but it should be noted that Saitama was still fairly weak at this time.
References