Indo-Pacific: Red Sea and East Africa to Samoa, north to southern Japan, southern Korea, and the Ogasawara Islands, south to Australia and Lord Howe Island. Palau and Yap in Micronesia. Sometimes enters freshwaters of East Africa (Lake Malawi) and Madagascar.

Dorsal and anal fins continuous with caudal fin. Four pairs of mouth barbels. A single highly venomous serrate spine at the beginning of the first dorsal and each of the pectoral fins.

The only catfish found in coral reefs. Also found in estuaries, tide pools and open coasts. Juveniles form dense ball-shaped schools of about 100 fish; adults are solitary or occur in smaller groups of around 20 and are known to hide under ledges during the day.