Parupeneus nansen – Nansen goatfish

Parupeneus nansen – Nansen goatfish ©FAO/M. Lipperi

The Nansen goatfish is a small, bottom-dwelling fish that inhabits coastal and reef environments of the Western Indian Ocean. For many years, it was misidentified due to its close resemblance to related species, which led to confusion in scientific records and fisheries data.

The discovery

On 30 September 2007, while sorting the catch from a trawl haul conducted off the southern coast of Mozambique at a depth of 45 m aboard the research vessel Dr. Fridtjof Nansen, P.C. Heemstra observed an unusual goatfish specimen with three distinctive red spots on its caudal fin. The specimen was set aside for photography. In October, three additional specimens exhibiting the same caudal fin coloration were collected nearby through trawling at a depth of 51 m. These four specimens were designated as the type specimens for Parupeneus nansen (the original specimens on which the description of a new species is based).

Additionally, seven more specimens of this species were found in the Bishop Museum fish collection, where they had been misidentified as Parupeneus heptacanthus. These specimens were collected during the International Indian Ocean Expedition in 1964 through trawling at a depth of 25–29 m off the northeastern coast of Somalia. However, there is no available information on their coloration when alive, and these specimens were not designated as paratypes (additional specimens used to help define the characteristics of a new species but secondary to the holotype, the primary type specimen).

Features and characteristics

The Nansen goatfish is a small, slender species with a moderately elongated body and 15 or 16 pectoral-fin rays. Its dorsal side is yellowish grey, with scales narrowly edged in red that gradually fade to silvery grey toward the ventral side. The head is prominently red on top, transitioning to silvery white along the cheeks and operculum, while the barbels are white. A distinctive feature is its caudal fin, marked by three deep pink-to-red spots – one on each lobe and one at the midbase. Although it closely resembles the Indo-Pacific Parupeneus heptacanthus, the Nansen goatfish can be distinguished by its unique coloration and comparatively shorter barbels and pelvic fins.

As are all other goatfish species, the Nansen goatfish is equipped with a pair of chin barbels, which are highly sensitive sensory organs. These barbels help them detect prey hidden in the sand, such as small crustaceans and worms, making them expert foragers on the seabed. As bottom-dwellers, goatfishes play a vital ecological role in cleaning up the seabed. By sifting through the sediment in search of food, they help aerate the substrate and recycle nutrients, benefiting the health of coral reef ecosystems.

Most goatfish species are social fish that commonly swim in schools. Beyond providing safety, these groups work together to disturb the seabed, uncovering hidden prey and turning the area into a shared feeding ground.

The Indo-Pacific genus Parupeneus, the second-largest in the family, is characterized by a single row of blunt, conical teeth in the jaws and the absence of teeth on the vomer and palatines (the bones on the roof of the mouth) which are present in other genera such as Upeneus.

Roof of mouth of a) Parupeneus (upper), and Upeneus (lower). ©FAO

Goatfishes play a significant role in both small-scale and commercial fisheries throughout tropical, subtropical and temperate waters. Their tendency to form schools and their rapid growth rates make them a favoured catch, particularly in coastal zones where fishers use nets, traps, and hook-and-line techniques.

Given their important function in maintaining the health of reef and seabed habitats, promoting sustainable fishing is essential to preserve populations of goatfishes and support the overall balance of marine ecosystems.

Geographical distribution

Western Indian Ocean: from Mozambique to Somalia.

P. nansen photographed by O. Alvheim (Norwegian Institute of Marine Research) ©O. Alvheim/FAO

Resources

• Randall, J.E.; Heemstra, E. (2009). Three new goatfishes of the genus Parupeneus from the Western Indian Ocean, with resurrection of P. seychellensis. Smithiana Bulletin, 10: 37-50