Siphamia tubifer, also known as the sea urchin cardinalfish, is a small (~7 cm) coral reef fish in the family Apogonidae.

[4] Male S. tubifer are mouthbrooders, holding their fertilized clutches of eggs in their mouths and releasing the larvae when they are in the preflexion stage.

[5] S. tubifer is thought to acquire the bacteria through ingestion of seawater after its light organ has mostly developed.

[7] The luminescence system primarily consists of a ventral light organ that holds the bacteria and a shutter lens in the abdomen.

[8] One study showed that at twilight, S. tubifer left its urchin and luminesced to attract and feed on zooplankton near the ocean bottom.