This is a 'handfish',as identified in this National Geographic item. I keep imagining a bunch of these guys, maybe about goblin height, clutching wicked little spears. Maybe they aren't overtly hostile to man, just inhumanly indifferent to our non-aquatic lives.
"Man, is there anything Jeff CAN'T do when it comes to gaming? This guy is like a critical 20 every roll. Jeff can bite the heads offa five game geeks, including their sorry-ass DM, and spit 'em into a large duffel bag ONE AT A TIME!...that's just the kind of messed up bastard he is! You think yer a gamer, punk? Well..do ya? Jeff will depants your weasel-ass right in front of your grandma."