In my original universe, there are many unique species of merfolk. Some look more humanoid, the others more fish-like. This is a piscine merman of the Merrow clan. Most male Merrows are more piscine than their (usually) attractive female counterparts. Though with any merfolk species, any type of appearance is fair game. There also been piscine merfolk of other clans besides the Merrow, but Merrows are the most common fish-like of merfolk.