Its green to brown body has darker blotches and often whitish bands through the eye, along the midside and on the back; short skin flaps decorate the dorsal spine and body. Juveniles of both sexes look alike; approaching maturity, males develop an oblong patch of bristles on the caudal peduncle, which grows longer and curves backwards. It is often confused with Acreichthys radiatus, which is smaller (5 cm), lives on coral reefs and has four or more chalky-white bars. Do not confuse it either with Chaetodermis penicilligerus, covered in large tassels and reaching 30 cm.
It ranges from Sri Lanka to New Caledonia and southern Japan, on sheltered reefs down to 15 m, mainly in seagrass, weed and rubble areas; most specimens are caught at about 3 m. Rather than a true coral-reef fish, it lives on sand, mud and seagrass bottoms, hence its other name, seagrass filefish. It lives alone and raises its dorsal spine and ventral flap to impress rivals and mates.
Filefish lay adhesive eggs near the bottom. In the aquarium, German breeder Iris Bönig obtained clutches of about 300 eggs of 1 mm laid in sand and algae clumps and guarded by the female; they hatched in 3 days at 25 °C, and the fry, fed brine shrimp nauplii, reached the juvenile stage by about day 15. Captive-bred fish are also produced commercially (Biota, Palau). Females start carrying eggs at about 4.5 cm.
Its reputation comes from eliminating Aiptasia, and sometimes Manjano anemones. Biota's captive-bred fish are raised on Aiptasia: one aquarist saw such a fish clear his tank in about ten days. Yet stomach contents of wild fish contained no coral or anemone, and British trade professionals consider it a poor Aiptasia controller and not reef-safe.
