Lined Butterflyfish

The lined butterflyfish (Chaetodon lineolatus) is a marine ray-finned fish belonging to the family Chaetodontidae. It is one of the largest species in the genus Chaetodon and can be found in a wide range, from the 🌊 Red Sea to 🇿🇦 South Africa and as far east as southern 🇯🇵 Japan and Hawaii.

Taxonomically, it belongs to the subgenus Rabdophorus, which may potentially be recognized as a distinct genus. This group includes species such as the spot-naped butterflyfish (C. oxycephalus), black-wedged butterflyfish (C. falcula), and Pacific double-saddle butterflyfish (C. ulietensis). While these species differ in shape, they all share bluish vertical lines on a white body with yellow behind, as well as black on the back and caudal peduncle. They also exhibit the typical eyestripe of Chaetodon. Another species, the blue-cheeked butterflyfish (C. semilarvatus), is considered a more basal lineage of Rabdophorus, but it also displays the characteristic blue vertical lines.

The lined butterflyfish can grow up to 30 centimeters (12 inches) long, similar in size to dinner plates. They have a white coloration with thin black vertical bars that merge into a thick black band at the base of the tail and dorsal fin. The tail, dorsal, and anal fins are yellow.

This species is found along the east coast of Africa, including the 🌊 Red Sea and 🇲🇿 Mozambique Channel, as well as in Northern 🇦🇺 Australia, the Coral Sea, Gulf of Carpentaria, Timor Sea, and West Indo-Pacific regions encompassing the Java Sea, South China Sea, Philippine Sea, and Celebes Sea. Lined butterflyfish are typically found in pairs or swimming alone, occasionally forming spawning aggregations. They inhabit coral-rich areas of reefs and lagoons at depths ranging from 2 to 50 meters.

The lined butterflyfish has a diet consisting of coral polyps, small anemones, algae, and invertebrates. They are known to be territorial, which is linked to their specific feeding habits in certain areas. Individuals can reach a maximum age of ten years.

Regarding development, larvae of the family Chaetodontidae settle either in similar habitats to adult conspecifics, habitats with high coral cover, or entirely different habitats from those used by adult conspecifics. Juveniles remain in their current habitat until reaching maturity unless they have already reached post-settlement growth of over 100 mm, at which point they migrate to adult habitats.

Little is known about the spawning behavior of butterflyfish as a whole, but it is believed that they spawn near their feeding habitats during the new moon. Lined butterflyfish mate in lifelong monogamous relationships, although males have the choice to either stay with their mate or seek another mate to maximize their fecundity. These fish are social maters, spending time with their mate outside of spawning and often living together in the same habitat. However, they exhibit little to no parental care towards their young.

Lined butterflyfish are preyed upon by larger marine predators, including sharks, eels, and snappers. Loss of habitat and feeding grounds may intensify predation.

In terms of their ecosystem roles, corals and members of the family Chaetodontidae were traditionally believed to have a commensal relationship, with corals providing food and shelter for the butterflyfish. However, further research suggests that C. lineolatus and other corallivore members of Chaetodontidae pose a greater threat to coral than previously understood. Corallivores disrupt the growth of coral species, which can have long-term effects on reef biodiversity. The loss of habitat also makes reef fishes, including the Chaetodontidae, more susceptible to predation by larger fishes.

The IUCN classifies the lined butterflyfish as Least Concern due to its wide distribution and presence in protected areas. The main threat it faces comes from the loss of habitat due to coral reef degradation caused by excessive development and exploitation of coral reefs and their resources.