Castilleja aquariensis is a species of flowering plant in the broomrape family known by the common name Aquarius Plateau Indian paintbrush. It is endemic to Utah in the United States, where it occurs on the Aquarius Plateau, including Boulder Mountain. All occurrences are within the bounds of Dixie National Forest. This perennial herb grows 15 to 30 centimeters tall and blooms in inflorescences with small flowers and large light yellow bracts. It is probably "somewhat parasitic."