The Sicklefish, also known as the "horned butterfly fish" or "sea god statue," is a tropical saltwater fish that thrives in shallow reef waters. It is a popular species of ornamental fish due to its colourful and elegant appearance.

The Sicklefish boasts of a beautiful combination of black, white, and yellow colour blocks, with its scythe-like dorsal fins adding to its extraordinary air.

The English name "Moorish idol" originated from the early European breeders of the fish, who noticed a resemblance of the Sicklefish's face to that of the Moors.

Additionally, it is believed that the name may have also come from the Philippines' indigenous people, whom Magellan's fleet called "Moors," when the fleet arrived in the Philippine Islands in 1521 via the New World.

The locals greatly admired the abundant Sicklefish in their waters, thus naming it the "Moorish Idol."

Sicklefish is often found in small schools, sometimes aggregating in hundreds. Its habitat ranges from hard-substrate turbid harbours and reef platforms to deep trenches at clean reef margins up to 100 meters deep.

When threatened, they quickly hide in reef caves or crevices, while at night, they sleep on the seafloor, their bodies turning dark to avoid natural predators.

The Sicklefish belongs to the family Scyphocephalidae and is a tropical rocky reef fish with a unique appearance. Rocky reefs are found in rivers, lakes, and oceans, usually near the surface of the water, and provide a natural habitat for fish. Sicklefish lives a diffuse life in the outer sea, up until their body length reaches up to 40 mm, after which they move towards the reef.

Their flat and thin bodies are taller than long, with a prominent "rostrum mouth," long backs, and extended parts. Mature Sicklefish can grow up to 18 cm long and are yellowish with three striking black vertical stripes. Juveniles feed on plankton, while mature Sicklefish mainly feeds on non-coiled vertebrates and seaweed.

Juvenile Sicklefish is transparent with a silvery white belly, known as "grey sickle-fish." They have long dorsal fins, short snouts, and knife-shaped spines at the corners of their mouths, but lack the horns on their foreheads. The appearance and habitat of juvenile Sicklefish change as they grow. When they reach 40 mm in length, they move towards the coral reef area.

By the time they reach 75 mm, the knife-shaped spines at the corners of their mouth begin to disappear, and upon reaching maturity, the Sicklefish develops prominent horns on their foreheads, earning them the name "horned scyphozoans."

The Sicklefish is not only popular in the aquarium trade but also has cultural significance in some areas. In Hawaii, the Sicklefish is considered a sacred fish and is associated with the goddess of hula, Laka. The Sicklefish is also featured in some Pacific Islander myths and legends as a symbol of courage and strength.

Additionally, the Sicklefish is an important food source for some coastal communities, and its population has been impacted by overfishing and habitat destruction. Conservation efforts are being made to protect this unique and valuable species.

In conclusion, the Sicklefish is a beautiful and elegant tropical saltwater fish that has become a popular ornamental fish due to its striking appearance. Its unique features and behaviours, such as hiding in reef caves and crevices when threatened and sleeping on the seafloor at night, make it an intriguing species to study.

Its different life stages and transformation from "grey sickle fish" to "horned scyphozoans" add to its captivating appeal, making it a favourite among aquarium enthusiasts.