The Pajama cardinalfish is a very striking fish. With high raised dorsal fins and wide flared belly fins that are colored yellow, they stand quietly in the water. The eye is red in color and strikingly large. Young specimens have a yellow head, which fades as the fish ages. A black vertical line runs from the dorsal fin to just behind the ventral fins. Behind this line, light brown spots can be seen on the otherwise whitish body.
A characteristic of Cardinal bass is the dorsal fin that is made up of two parts. With Sphaeramia nematoptera, the front dorsal fin is colored yellow and the second dorsal fin is transparent, just like the pectoral, caudal and anal fins.
The eyes are so large because it is a nocturnal fish. Only at dusk does Sphaeramia nematoptera come out to look for food. During the day they hide in the dark parts of the coral reefs. You can often find this species in the neighborhood of Diadema setosum or Diadema antillarum. In the event of danger, they seek protection between the long spines of these sea urchins.
Biotope