Batrachoididae is the only family in the ray-finned fish order Batrachoidiformes. Fish in this family are usually called toadfish: both the English common name and scientific name refer to their toad-like appearance (batrakhos is Greek for frog).

Toadfish are benthic ambush predators that favor sandy or muddy substrates where their cryptic coloration helps them avoid detection by their prey. Toadfish are well known for their ability to "sing", males in particular using the swim bladder as a sound-production device used to attract mates.

Toadfishes are usually scaleless, with eyes set high on large heads. Their mouths are also large, with both maxilla and premaxilla, and often decorated with barbels and skin flaps. They are generally drab in colour, although those living coral reefs may have brighter patterns. They range in size from 7.5 centimetres (3.0 in) length in Thlassophryne megalops, to 57 centimetres (22 in) in the Pacuna toadfish.

The gills are small and occur only on the sides of the fish. The pelvic fins are forward of the pectoral fins, usually under the gills, and have one spine with several soft rays. There are two separate dorsal fins; the first is smaller with spines, while the second has from 15 to 25 soft rays. The number of vertebrae range from 25 to 47.