Common name: Pajama Cardinalfish, Polka-dot Cardinalfish, Spotted Cardinalfish
Scientific name: Sphaeramia nematoptera
Max size: 3 in / 7.5 cm
pH: 8.1-8.4
Salinity: 1.020-1.025
Temperature: 72-78ºF (22-26°C)

The Pajama cardinalfish is a very hardy fish and one of the best choices for a beginner who wants to start keeping tropical marine fish. They are very forgiving and can tolerate less than perfect conditions and might even spawn in the aquarium even if you aren't an expert. The Pajama cardinalfish is also cheap and readily available in most stores selling marine fish, including online stores. All this adds up to making it a perfect beginner fish.

The Pajama cardinalfish is a friendly species that can be kept in a community aquarium with other peaceful tropical marine fish species. They should never be kept with large or aggressive species. The Pajama cardinalfish is reef safe but not invertebrate safe meaning that it will leave corals etc alone but might eat small ornamental shrimp and other mobile invertebrates.

The pajama cardinalfish originates from the western part of the Pacific Ocean. It can be found from Java eastwards to Fiji. The northern distribution limit is the Ryukyu Islands of Japan and the southern limit is the Great Barrier Reef.

Pajama Cardinalfish care and aquarium setup

The Pajama cardinalfish should not be kept in an aquarium smaller than 30 gallon /120 L. A larger aquarium is recommended if you want to keep a large school. The aquarium should be decorated with a lot of hiding places and it is good if there are a few overhangs large enough for the Pajama cardinalfish group to hide under during the day. They appreciate patches of sea grass. In the wild they often hide among the spines on sea urchins and they love if you can decorate a small area in the aquarium to mimic se urchin spines. You can use whatever bottom substrate you see fit.

The pajama cardinalfish prefers a softer lit aquarium.

Ideal conditions for the Pajama cardinalfish is pH 8.1-8.4, salinity  1.020-1.025, and temperature 72-78ºF (22-26°C).

Feeding Pajama Cardinalfish

The Pajama cardinalfish is easy to feed as they will accept most foods, including flake food. It is important to give them a varied diet that contains all the nutrients they need. To this end you should feed them a varied diet containing frozen food, flake food and finely chopped sea food. The Pajama cardinalfish appreciates to be fed live food every now and then. Feed your fish 2-3 times a day.

Breeding Pajama Cardinalfish

Sexing the Pajama cardinalfish is hard but males usually have a longer secondary dorsal fin than females and the females have somewhat rounder bodies than males.

The Pajama cardinalfish can be breed in aquariums and are relatively easy to breed. Once a Pajama cardinalfish pair have started breading they will breed regularly and often. The species is a mouth brooder and the male carries the eggs. The Pajama cardinalfish pair will be very aggressive during the spawning period. The male will protect the female until he takes the eggs in his mouth, after that the female will protect the male and chase away other fish. The male carries the eggs and fry in his mouth for about 3-4 weeks. He doesn't eat during this period.

Pajama cardinalfish fry are large and can eat newly hatched brine shrimp as soon as they are released. The fry are aggressive and more aggressive fry will force weaker fry away from the food. It can be a good idea to separate aggressive and non aggressive fry into different aquariums if you want a higher survival rate. The fry grow rather fast and is not as sensitive as many other marine fish fry.

Cardinalfish Articles:

Bangaii Cardinalfish – Pterapogon kauderni