Chaetodon speculum also commonly referred as Oval-spot Butterflyfish and Mirror butterflyfish is bright yellow with a large black mark on the upper side of the body. It has a black bar through the eye and a translucent caudal fin margin. The fins are all yellow. It has a compressed body and grows to a maximum length of18cm. The Mirror butterflyfish is sometimes confuses with Chaetodon bennetti, the latter has blue lines. The yellow colour is the main difference with Chaetodon unimaculatus.
The Oval-spot Butterflyfish is distributed in the tropical waters of the eastern Indian Ocean eastward throughout the Indo-Malayan region to Tonga, northward to southern Japan, southward to Lord Howe Island. Widely around the coral reefs in Taiwan. It inhabits Coastal reef slopes with hydroids and anemones. Juveniles shelter in coral thickets. Usually solitary. Found at depths from 3m to 30m.
In the wild Chaetodon speculum feeds on coral polyps and invertebrates.
Butterflyfish are not recommended for reefs as they will pick at or eat a wide variety of corals, fan worms, and other invertebrates. Most Butterflyfish are known to pick at Aiptaisia, a parasitic anemone.