Description

• Scientific Name: Sphaeramia nematoptera
• Common Names: Pajama Cardinalfish, Polka-dot Cardinalfish, Spotted Cardinalfish
• Maximum Length: 3.3 inches (8.5 cm)
• Minimum Aquarium Size: 30 gallons (113 liters) for a small group; larger tanks support their schooling behavior and reduce stress.
• Foods and Feeding Habits: Carnivorous, preying on zooplankton and small crustaceans in the wild. In aquariums, offer frozen mysis shrimp, brine shrimp, or copepods; may accept high-quality flakes once acclimated. Feed small amounts 1-2 times daily, preferably at dusk to match their nocturnal habits.
• Reef Safety: Reef-safe; they don’t harm corals or invertebrates and integrate well into reef communities.
• Temperament: Peaceful and schooling; best kept in groups of 3 or more for natural behavior. Avoid aggressive tankmates to prevent bullying.
• Description: The Pajama Cardinalfish is a charming nocturnal species with a whimsical look. Its body features bold vertical stripes in yellow, black, and red, dotted with iridescent spots and a large false eye on the dorsal fin. Native to the Indo-Pacific, from Indonesia to Papua New Guinea, they inhabit sheltered reefs and mangroves at depths of 1-14 meters. Easy to care for in groups, they add a serene, hovering dynamic to low-light tanks.

Fun Facts:

• Males are mouthbrooders, incubating fertilized eggs in their mouths for 7-10 days without eating, then releasing free-swimming fry that need tiny foods like rotifers to survive.
• One of the few cardinalfish successfully bred in home aquariums, with pairs spawning under dim lighting and producing up to 200 eggs per clutch in mature reef setups.
• Their “pajama” name comes from the striped pattern resembling sleepwear, but in the wild, they form loose schools around mangrove roots for protection during the day.