Atlantic Sergeant Major
Abudefduf saxatilis
Damselfish
damselfish
About
Damselfish are small, feisty reef fish found on tropical reefs around the world. In this app the group includes the threespot dascyllus, the Indo-Pacific sergeant, and the blue-green damselfish.
How to tell it apart
Look for a small, deep-bodied fish that darts at you or other fish near a patch of coral or rock. That bold, territorial defence of a small home patch is a strong sign you are looking at a damselfish. Within the group, tell members apart by colour pattern, stripes or spots, and tail shape.
Appearance
Most damselfish are small fish, though the biggest species can reach 30 cm, about the length of your forearm. Body shapes are compact and oval, with colours ranging from plain grey to bright blue, yellow, or striped patterns.
Habitat
Most damselfish live on tropical and subtropical rocky or coral reefs worldwide. A few species live in fresh or brackish water instead of the sea, and some, like the Garibaldi, live in cooler subtropical waters such as the coast of southern California.
Behaviour
Many damselfish are strongly territorial and will defend a small patch of reef against other fish. Some species spend almost their whole life within this one small territory.
Diet
Damselfish eat small crustaceans, plankton, and algae. Some species spend most of the day foraging, feeding higher in the water when currents are slow and closer to the bottom when currents pick up.
Breeding
Male damselfish court females with a display called the signal jump, swimming up and then rapidly back down while making pulsed sounds. Females choose mates based on how vigorously they perform this display, and males then guard the eggs.
Log it in Into the Blue
Describe what you saw and we name it, then keep every species you find in your Oceandex.
