Humbug

Overview

The Humbug (Dascyllus aruanus) is a small, highly territorial damselfish widely recognized for its striking black-and-white pattern. These fish are obligate coral dwellers, typically found living in close association with branching stony corals like Acropora, which provide them with essential shelter.

Distribution & habitat

This species is native to the Pacific Ocean, ranging from the region north and east of the Lombok Strait to the Line, Marquesan, and Tuamotu islands, extending north to southern Japan and south to New Caledonia. They inhabit shallow tropical lagoons and subtidal reef flats, usually at depths between 0 and 20 meters.

Appearance

The Humbug has a deep, compressed body characterized by a white base color marked by three broad, vertical black bars. A distinctive large brown or dark spot is often present on the snout between the eyes. Their pelvic fins are black, while the pectoral fins are transparent and the caudal fin is pale. Adults typically reach a common length of about 6 cm, though they can grow up to 10 cm.

Biology & behavior

These fish are social, often forming groups or harems consisting of a dominant male and several females. They exhibit protogynous hermaphroditism, meaning individuals can change sex from female to male if the social structure requires it. They are known to be quite aggressive, particularly when defending their coral territory or nesting sites. They also produce audible sounds during social interactions, such as territorial disputes or mating.

Feeding

As omnivores, they forage in the water column on zooplankton and also consume benthic invertebrates and algae. By living within coral branches, they may also help the coral by removing unwanted algal growth.