Pajama Cardinalfish (Sphaeramia nematoptera) The Pajama Cardinalfish is a peaceful, nocturnal reef fish with a quirky and unmistakable appearance. Its body features a greenish-yellow face, a bold red eye, and a midsection marked by a black vertical band, followed by a speckled rear half covered in red-orange polka dots—resembling a pair of colorful pajamas. Calm and easygoing, this species is a favorite for both beginner and experienced aquarists. Tank Requirements Pajama Cardinals do well in tanks of 30 gallons or more, with moderate flow and ample rockwork to provide hiding spots and shaded areas. As schooling fish, they are best kept in small groups (3 or more) to encourage natural social behavior, but ensure adequate space to prevent bickering within the group. They adapt easily to both reef and fish-only systems. Peaceful and Reef-Safe These cardinalfish are completely reef-safe, posing no threat to corals or invertebrates. Their peaceful nature makes them ideal for community aquariums, where they typically keep to themselves or their group. While mostly active at night, they adapt to aquarium lighting schedules and become more visible during the day. Diet and Feeding Pajama Cardinals are carnivorous and easy to feed, readily accepting a wide range of foods. Offer high-quality frozen foods like mysis shrimp, brine shrimp, and finely chopped seafood, along with meaty pellets and flakes. Feedings should be small and frequent, especially in systems with strong competition for food. Tankmates and Behavior Naturally peaceful and slow-moving, Pajama Cardinals are excellent companions for other non-aggressive fish, including gobies, blennies, clownfish, and wrasses. Avoid pairing them with fast, boisterous or aggressive tankmates that may outcompete them at feeding time. In groups, they exhibit mild pecking order behavior but rarely cause real harm. They are also known for hovering motionless in mid-water, adding a calm, mesmerizing dynamic to any tank.
