also known as the Blacktail Parrotfish or Yellowstreaked Parrotfish, is a species of marine fish belonging to the Scaridae family. They are found in the Western Atlantic Ocean, ranging from Florida in the United States to Brazil, and are commonly seen in coral reefs and rocky areas at depths of up to 60 meters.

Swarthy Parrotfish are a medium-sized species, growing up to 45 cm in length, with a deep, compressed body and a sloping forehead. They have a pointed snout, sharp teeth fused together to form a beak-like structure, and a single dorsal fin that runs the length of their body. Their body coloration varies between individuals, with adults typically having a yellowish-green or brownish-black body, and a distinctive bright yellow streak running from their eye to their pectoral fin. Their tails are black, hence their alternative name, Blacktail Parrotfish.

The social behavior of Swarthy Parrotfish is unique compared to other species of parrotfish. They are known to form small groups consisting of one dominant male and several females. The male is responsible for protecting the group, and will actively chase off intruders or predators. During the day, Swarthy Parrotfish can be seen grazing on algae and seagrass, using their beak-like teeth to scrape algae off of rocks and coral. At night, they seek shelter in crevices and under ledges to sleep, where they are less vulnerable to predators.

Like other species of parrotfish, Swarthy Parrotfish play an important role in maintaining the health of coral reefs. They are known for their ability to graze on algae, which can overgrow and smother coral, and for their role in producing sediment by excreting sand and other debris. They are also a popular game fish, prized for their flesh and often caught by recreational anglers.

In terms of conservation status, Swarthy Parrotfish are not currently considered threatened. However, like many species of parrotfish, they are susceptible to overfishing, habitat loss, and pollution. It is important to manage and protect their habitats to ensure their populations remain healthy and sustainable.