The butterflyfish family is a large and well known group of tropical species. They are mostly of small size with oval-shaped bodies which are deep and greatly compressed. The dorsal fin is continuos along the back and is not divided between the anterior spinous part and the spineless posterior portion. The tail may be rounded, truncated, or emarginated on its posterior border, but is never forked. The head bears a small mouth which contains flexible, brush-like or comb-like teeth. Within this family some members have a sharp spine on the lower back corner of the preopercle. These are true angel fishes, and with the presence of this spine can be distinguished and separated from true Butterfly Fishes, placing them in a separate family, Pomacanthidae.
Butterflyfish are seen in various colors with bright and vivid hues of yellow, blue, red, orange, black and white. A few are of somber or muted colors, and many possess a dark stripe that runs through the eye. This family occurs in all tropical waters, but the largest number occurs in the tropical western Pacific and Indian Oceans. There are well over one hundred different species of butterflyfish, and many of them will be found throughout the region. When planning to dive and survey these delightful fish, check with your dive centre which species you are most likely to encounter. You will also find complete listings, descriptions and images for the area that you are diving in at the excellent www.fishbase.org web site.
One of the larger butterflyfish that can be found throughout the region is the Saddle Butterflyfish (Chaetodon ephippium). This species has an overall colour of yellowish grey with a large black spot bordered below by a broad white band on the back, and wavy blue lines on the lower sides. You are likely to encounter it in lagoons and seaward reefs to a depth of 30 m. It prefers coral-rich and clear water areas. They occur singly, in pairs or small groups. The maximum adult length is 30cm.