- Any of various usually colorful fishes of the family Ostraciidae of warm coastal waters, having a boxlike shape with the body enclosed in bony armorlike plates.
- Any of various similar fishes of the family Aracanidae of deep temperate waters.
- A name of sundry plectognath fishes of the suborder <em>Gymnodontes</em> and family <em>Tetrodontidœ.</em>
- The trunkfish.
- Any of the <xref>family</xref> Ostraciidae of <xref>squared</xref>, <xref>bony</xref> <xref>fish</xref>, closely related to the <xref>pufferfish</xref> and <xref>filefish</xref>.
- any of numerous small tropical fishes having body and head encased in bony plates