Blood Feeder (5e Creature)
From D&D Wiki
Small monstrosity, lawful evil
Water Breathing. The blood feeder can breathe only underwater.
Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 13 (3d6 + 3) piercing damage.
Blood Feeders are mutated carnivorous fish which have been exposed to the gory waters of the Crimson, the region surrounding the brain of Cthulhu's lair. Like the piranha, these swarming fish thirst for blood. Birthed from tainted blood themselves, their hunger is truly intense.