Orbicular Cardinalfish

The orbiculate cardinalfish, also known as the chubby cardinal or polka-dot cardinalfish (Sphaeramia orbicularis), belongs to the family Apogonidae. This species reaches an average total length of approximately 10 cm, with a common length of 8.9 cm. It is characterized by a thin, dark vertical band around its midsection and scattered dark spots near the tail region. The species inhabits depths ranging from 1 to 5 meters.

Visually, the orbiculate cardinalfish is greenish-grey, featuring a prominent dark vertical bar extending from the origin of the spiny dorsal fin to just before the anus. Its body, head, and the membrane of the first dorsal fin are adorned with scattered spots, and its pelvic fins are notably dark.

This species is typically found in coastal waters, forming small aggregations among mangroves, rocks, debris, or shallow, sheltered shoreline piers. The orbiculate cardinalfish primarily feeds at night, with feeding activities peaking in the early evening and just before daybreak. Its diet predominantly consists of planktonic crustaceans. Courtship and spawning follow a fortnightly cycle, occurring shortly before new and full moons. During this period, there is distinct pairing for courtship and spawning. The species exhibits mouthbrooding behavior, with males incubating up to 12,000 eggs for approximately eight days until hatching. The pelagic larval phase is followed by juvenile settlement, during which growth occurs at a rate of 3 to 6 mm per month. Sexual maturity is reached at a length of 7 cm for males and 6 cm for females.

The orbiculate cardinalfish is distributed across the Indo-Pacific region, spanning from East Africa to Kiribati, extending north to the Ryukyu Islands (🇯🇵 Japan) and south to 🇳🇨 New Caledonia (🇫🇷 Overseas France). Its range also includes Belau and the eastern Caroline and Mariana Islands in 🇫🇲 Micronesia.