Apogon leptacanthus. The Threadfin Cardinal, also known as the Glass Cardinal or Longspine Cardinal, has a translucent/silver body and will display reflective abilities. The Threadfin Cardinal is incredibly hardy and easily adapted to any home aquarium. They feed well, are friendly, and can be housed with any types of fish, corals, or inverts. The Threadfin Cardinal is nocturnal so it can be best to feed them at night when they are most active. They prefer tanks with plenty of live rockwork providing them places to hide. The feed on a diet consisting primarily of frozen meaty foods.