Neoglyphidodon melas

Lore & Background

Neoglyphidodon melas may be identified by its dark blue-black coloration in adulthood, while juveniles are pale blue with a yellow stripe across their dorsal surface and sport yellow-lined caudal fin rays and bright blue anal and pelvic fins with dark outer rays. The body is laterally compressed, allowing this species to navigate through tight crevices in coral reefs, and its long pectoral fins further aid in maneuverability and agility. It may grow to 11.8-18 cm and reach 100 g at maturity.

This species may be confused with Chrysiptera brownriggii (the surge damselfish), since both inhabit shallow lagoons and coral reefs and have small, compressed body plans with blue and yellow stripes at some point in their lives. However, Chrysiptera brownriggii has a yellow body with a blue dorsal surface, while juvenile Neoglyphidodon melas has a yellow dorsal surface and light blue body. Neoglyphidodon melas is found throughout the Indo-Pacific region, including the Red Sea, East Africa, the Indo-Malayan archipelago, the Ryukyu Islands, China, the Philippines, Palau, New Guinea, the Solomon Islands, Vanuatu and northern Australia, typically between depths of 1-12 m in coralline, rocky lagoons and marine reefs with soft corals.

Bowtie damselfish are coprophagous organisms: adults feed on the nutrient-rich feces of giant clams (Tridacna gigas), while larval bowtie damselfish feed solely on plankton and live around Acropora coral stalks. Juvenile bowtie damselfish feed mainly on soft corals, which constitute 87% of their preferred diet. Once mature, a fish finds its own giant clam to live near, consuming its excrement in addition to soft corals. Adults lacking a residential giant clam display higher aggression, likely due to food instability.

Reader's Guide

Neoglyphidodon melas holds significance as a species that illustrates a specialized ecological niche: its adults are coprophagous, relying on the feces of giant clams (Tridacna gigas) for essential proteins that increase survival and reproduction. This dependency ties its fate to the health of giant clam populations. The species also serves as an important prey for higher trophic level fish such as the coral grouper (Plectropomus leopardus), which supports local fishing industries in the Indo West Pacific.

Its conservation status is least concern according to the IUCN, but the species faces multiple pressures. In the Seribu Islands, it is commonly caught as bycatch in fishing pots; small individuals are discarded, often posthumously, and released fish suffer high mortality from air-exposure, handling, and relocation. Overfishing and lack of escape vents in pots have led to reduced egg yields and population declines in some areas. In the Red Sea, stress from catch makes the fish vulnerable to infection by Tenacibaculum maritimus, which causes anorexia, erratic swimming, hemorrhagic skin, oral ulcers, and fin rot, with 60% mortality. Anthropogenic underwater noise from aquaculture and boats reduces reaction speeds and response distances, potentially lowering survival. Additionally, the disappearance of Acropora corals due to climate change threatens larval and juvenile bowtie damselfish, which rely on these corals for protection and food access. Despite these challenges, the species remains of least concern, though new infections, increased catch rates, and sound stress may indicate a troubled future.

Did You Know?

• Juveniles are pale blue with a yellow dorsal stripe, while adults are dark blue-black.
• The species is commonly caught as bycatch in fishing pots on the Seribu Islands.
• Infection by Tenacibaculum maritimus in Red Sea populations causes up to 60% mortality.