Pajama Cardinalfish

A hardy and peaceful fish that can live many years in a marine aquarium.

The Pajama Cardinalfish (Sphaeramia nematoptera) is a species of fish belonging to the Apogonidae family. Pajama Cardinalfish, also known as Polka-dot Cardinalfish or Spotted Cardinalfish, has a greenish-yellow face with orange eyes. The midsection is silver with bold, black scalar margins and the posterior section of the body is silver with orange polka-dots.


It grows to a total length of about 2.5 inches (8.5 centimeters) and features distinctive red eyes and a broad dark vertical 'waistband' with scattered red spots toward the tail. It is considered to be of low vulnerability, and is distributed throughout much of the West Pacific, from Java to Fiji, and from the Ryukyu Islands south to the Great Barrier Reef. In Pajama cardinalfish, males incubate the eggs in their mouth until they hatch.

Popular Aquarium Fish

The Pajama Cardinalsfish are an excellent choice for the beginning saltwater aquarist. They transport well, are inexpensive and adapt well to aquarium life. They can also be bred in captivity, so tank raised specimens may be available. They should have a tank of at least 40 gallons with rocky areas, caves and medium lighting. Pajama Cardinals swim slowly and usually do not shy away from spectators.

As they are a social fish, it is common to keep them in groups of five or more. They have been known to breed in captivity, unlike most marine fish, but captive bred specimens are only rarely available. If they are kept with a long spined sea urchin they will hide among the spines when they feel threatened.

During the day, Pajama Cardinalsfish tend to hover in groups in one place and like to remain stationary under rock ledges. In the wild they hide among sea urchin spines when they are threatened. Anything that simulates this arrangement is a useful addition to the tank. At night, Pajama Cardinals become solitary and hunt for food, covering the same feeding patterns that damsels do during the day. This has given them the title of damsel of the night.