The Crown Squirrelfish (Sargocentron diadema) is a species of tropical fish found in the Western Pacific, particularly around coral reefs in Indonesia, the Philippines, and Papua New Guinea. It belongs to the family Holocentridae, commonly known as squirrelfishes, which includes around 70 species of mostly small to medium-sized fish.

The Crown Squirrelfish typically grows to about 20-25 centimeters (8-10 inches) in length, with a maximum reported size of 30 centimeters (12 inches). It has a moderately deep, compressed body with a broad head and large eyes. The dorsal fin runs the length of the body and is divided into two sections, the first spiny and the second soft. The caudal fin is forked and the anal fin has three spines followed by soft rays.

This species is easily recognizable by its striking coloration. Its body is a deep red to pinkish color with three distinct white or pale pink stripes running the length of its body. The stripes are bordered by thin, black lines that give the fish a bold, ornate appearance. Its large eyes are also striking, with a bright red iris and black pupil.

Crown Squirrelfish are primarily nocturnal and tend to hide in crevices and under ledges during the day. At night, they venture out to feed on small fish, crustaceans, and other invertebrates. They are known to be territorial and aggressive towards other fish, particularly members of their own species.

In terms of fashion, the Crown Squirrelfish is not commonly kept as an aquarium fish due to its territorial and aggressive behavior. However, its striking coloration and bold patterns make it a popular subject for underwater photography and diving enthusiasts. In some parts of its range, it is also occasionally caught for food, though it is not considered a major target of commercial fishing. Overall, the Crown Squirrelfish is a fascinating and beautiful member of the squirrelfish family that adds a vibrant splash of color to the coral reefs of the Western Pacific.