Atrosalarias fuscus

Atrosalarias fuscus, commonly known as Black sailfin blenny, is a medium-sized blenny. These blennies are almost completely dark-brown to black

These fish inhabit shallow reefs where they live solitary between live and dead coral. In an aquarium they're reef safe and a very good algae eater. They're quite territorial though, so best place them as one of the last fishes in the tank and only in a tank big enough to form a territory and leave room for the other fishes. Don't combine them with other blennies, unless you've a very large tank with many hiding spots. They feed mainly on algae and if there is little algae in the tank high quality algae flakes or pellets should be supplemented!