Ostichthys daniela – Daniela’s soldierfish

Ostichthys daniela – Daniela’s soldierfish ©FAO/E. D’Antoni

Daniela’s soldierfish is a bright, red-coloured fish found in the mesophotic (twilight) coral ecosystems of the eastern Indian Ocean. It belongs to a group of fishes characterized by large eyes, strong fin spines and heavy spiny scales covering the body. The common name “soldierfishes” derives from their red coloration, evoking the red military uniforms worn by infantry in the 18th century (it’s a practical colour, as blood spots don’t show up on it).

The discovery

It is 5:46 am on 21 May 2015, and the research vessel Fridtjof Nansen is cruising off the southern coast of Myanmar. A three-man team from the Norwegian crew is hauling the trawl net back up to the deck from a depth of 121–129 m. FAO’s taxonomist, Peter N. Psomadakis, is watching them, unaware that shortly he will be experiencing one of the most exciting moments of his career. The fishes in the catch are an uprising of colour, sizes and shapes swirling in all directions, but Peter’s attention is caught by two bright red soldierfishes. He immediately photographs them and takes a fin clip for molecular analysis. Then he spends the next two hours taking counts and measurements, compares geographical range information, written descriptions and illustrations – and concludes that the collected soldierfishes are most probably undescribed species new to science. Following the survey, Psomadakis joins forces with David W. Greenfield and John E. Randall – two specialists of the group – to publish a revisionary paper on soldierfish where the two new species are formally described. With great romantic style, he dedicates one of the newly discovered soldierfish species to his wife, Daniela, as a token of his love and gratitude for her constant encouragement and support throughout his career!

Features and characteristics

Like other members of the group, Daniela’s soldierfish is characterized by an oval body covered with heavy spiny scales, large eyes, strong fin spines and bright red coloration. It is included in a subgroup of soldierfishes with three and a half scale rows above the lateral line, and resembles the rounded soldierfish Ostichthys convexus (also discovered on the 2015 Myanmar survey). The latter is distinguished from O. daniela by its convex head profile, stouter caudal peduncle, and more lateral-line scales and opercular scale rows.

No information is available on the diet and habits of Daniela’s soldierfish. Most likely, it takes shelter within the reef during the day, coming out at night to feed on plankton and small crustaceans. Its large eyes are well suited for low-light conditions, making these fishes well adapted for nocturnal feeding and twilight habitats such as mesophotic coral ecosystems.

Its bright red colour helps Daniela’s soldierfish blend into the dim waters of its mesophotic reef habitat as red light is rapidly absorbed by seawater at depth (red fish become almost invisible in the deep sea because red light is not present there).

Mesophotic coral ecosystems characterized by the presence of light-dependant corals – typically found at depths between 40 m and 150 m in the Bay of Bengal – are its home. It usually swims close to the seabed in hard-bottom habitats.

Geographical distribution

Endemic to Myanmar.

Resources

• Greenfield, D. W., Randall, J. E., & Psomadakis, P. N. (2017). A review of the soldierfish genus Ostichthys (Beryciformes: Holocentridae), with descriptions of two new species from Myanmar. Journal of the Ocean Science Foundation, 26, 1–33. https://doi.org/10.5281/zenodo.344964 .