Crescend-tail Bigeye

The Priacanthus hamrur, commonly known as the lunar-tailed bigeye, goggle eye, or moontail bullseye, is a species of marine fish within the Priacanthidae family.

This particular species is not frequently encountered but has a wide distribution in the Indo-Pacific region. Its range extends from the 🌊 Red Sea and southern Africa to 🇵🇫 French Polynesia, southern 🇯🇵 Japan, and 🇦🇺 Australia. There have also been reports of sightings at Easter Island. In addition, two records of Priacanthus hamrur have been documented in the Mediterranean Sea off 🇹🇳 Tunisia and 🇹🇷 Turkey.

Priacanthus hamrur is typically found in association with reefs, inhabiting tropical marine waters along outer reef slopes, rocky areas, and lagoons. Their preferred depth ranges from 8 to 250 meters, although they are most commonly found between depths of 30 to 50 meters.

Upon reaching sexual maturity, male Priacanthus hamrur typically grow to a size of 18-19 cm (7.1-7.5 in), while females typically reach a slightly larger size of 19.1-20.0 cm (7.5-7.9 in). Males can occasionally grow up to a maximum length of 45 cm. These fish have a relatively deep and laterally compressed body, with large red eyes (even when displaying a silver-colored appearance). Their mouth is oblique with a protruding lower jaw and small conical teeth. The dorsal fin consists of 13 to 15 soft rays, while the pelvic fins are notably large. The caudal fin displays a concave indented margin, which may have a crescent shape, hence the common name.

The coloration of Priacanthus hamrur can vary depending on the stage of development. It ranges from orange to entirely red or silver, occasionally displaying wide red bands on a silver background (the first red bar crosses the eye). These fish are also capable of rapidly changing their coloration. Some individuals may have a row of approximately fifteen small dark spots along the lateral line or large spots on the upper side. The fins display shades of red to light pink.

It is worth noting that Priacanthus hamrur bears resemblance to other species, namely Priacanthus blochii and Heteropriacanthus cruentatus. These species differ primarily in the shape of their caudal fin, which is only slightly rounded in comparison.

As for their diet, Priacanthus hamrur primarily feeds at night on small fish, small crustaceans, and various invertebrates such as small cephalopods, shrimp, crabs, and polychaete worms. These fish can be found year-round, with a peak in abundance during the month of August. Eggs, larvae, and very young juveniles of this species are pelagic in nature. While they typically live solitarily, there are instances where small aggregations or even large schools are observed in open waters.