Ostracodermi Ostracioidea or Ostracioidei, the boxfishes, is a suborder of ray-finned fishes belonging to the order Tetraodontiformes, which also includes the pufferfishes, filefishes and triggerfishes.

[1] The 5th edition of Fishes of the World classifies this clade as the suborder Ostracioidea within the order Tetraodontiformes.

[3] Ostracioidea contains two extant families and two extinct families:[2][4] Ostracioidea boxfishes share the head and much of the body, apart from the cheeks, being encased in a carapace made up of thick, typically hexagonal, inflexible plate-like scales.

The cross section of the body shows slight lateral compression with at least two angles or ridges.

[6] The largest species in the suborder are the scrawled cowfish (Acanthostracion quadricornis) and the buffalo trunkfish (Lactophrys trigonus) each with a maximum published total length of 55 cm (22 in),[7] while the smallest species are just above 10 cm (3.9 in) in length.