Diagnostic characters: Small to medium-sized fishes with elongate, compressed body that tapers
posteriorly. Body without scales or bony plates. Lateral line complete, running along middle of body
and extending nearly to caudal-fin base. A dendritic organ, located along ventral midline of body just
anterior to anal-fin origin and posterior to anus, found in all marine, and some fresh-water species.
Head broad, slightly depressed. Dorsal profile of head from snout tip to dorsal-fin origin straight or arched.
Mouth surrounded with barbels in 4 pairs; 1 pair between widely separated anterior and posterior
nostrils; 1 pair at corner of mouth and 2 pairs on lower jaw. Posterior nostril slit-like, located at base of
nasal barbel; anterior nostril with rounded opening; anterior nostril located either above upper lip margin or
within fleshy lip. Teeth present on jaws, except on upper jaw of some fresh-water species. Palate with
teeth, often molariform; molariform teeth sometimes found in lower jaw. Dorsal and pectoral fins
located just posterior of head, each with a pungent serrated spine at leading edge; fin spines venomous
and capable of producing painful sting; anal fin long and continuous with rounded or pointed
caudal fin; dorsal series of procurrent caudal-fin rays consists of elongate rays which, in marine
species, extend the fin anteriorly to at least vertical line at anal-fin origin, thus forming a second
dorsal fin that is continuous with caudal fin; dorsal adipose fin absent. Colour (in preservative): tan,
brown, or black on sides and dorsum; lighter ventrally; sometimes with light stripes along side of body,
extending onto head.
Habitat, biology, and fisheries: Found in fresh, brackish, and marine waters of tropical and subtropical
regions of the Indo-Pacific. Fresh-water species are restricted to Australia and New Guinea; marine
species are widespread along continental and island margins, especially in estuaries, lagoons, sand flats,
and reefs. Marine species sometimes found in river mouths in nearly fresh waters.
Large individuals seen beneath overhangs, in caves, and crevices. during daylight hours. Juveniles of
some species, especially Plotosus lineatus, seen on reef flats in ball-like aggregations. Feed primarily on
crustaceans, molluscs, and fishes. Incidental catch throughout range; taken by beach seine, trawl, and on
hook-and-line. Marketed mostly fresh and locally may be important.