The Castroi class was a Xindi-Insectoid shuttlecraft in service since at least the 22nd century. In the 2150s, ships of this class served as scoutships. By the early 25th century, Castroi-class fighters were auxiliary vessels of Olaen-class heavy escort carriers. (ENT episode: "Hatchery", STO video game: Delta Rising Xindi Terrestrial Lockbox)