Slender Sunfish

The slender sunfish, scientifically named Ranzania laevis, is a unique fish belonging to the family Molidae and is the only living species in the genus Ranzania. This fascinating fish is found worldwide in both tropical and temperate seas. It can grow up to a length of 1 meter (3.3 feet), residing primarily in the ocean's pelagic and epipelagic zones at depths ranging from 1 to 140 meters. Although this fish is generally solitary, it is sometimes seen in strandings, including notable events on beaches near Albany, Western Australia.

Characterized by its elongated body and unique vertical mouth slit, the slender sunfish lacks dorsal and anal spines and instead is equipped with 18 dorsal soft rays and 20 anal soft rays. In its early life stages, it has a caudal fin, but this is eventually reabsorbed and replaced by a structure called a clavus as it matures.

The slender sunfish is a cosmopolitan species, inhabiting areas across diverse regions. In the Atlantic Ocean, it is found from 🇺🇸 Florida to 🇧🇷 Brazil on the western side and from Madeira to Scandinavia on the eastern side. It also frequents waters off 🇿🇦 South Africa, and it is present across the Pacific from central 🇺🇸 California to 🇨🇱 Chile. In the 🌊 Indian Ocean, it can be seen around 🇲🇬 Madagascar, 🇲🇺 Mauritius, Reunion, and 🇦🇺 Australia. It occupies parts of the West Pacific, such as 🇯🇵 Japan, 🇨🇳 China, 🇹🇼 Taiwan, and 🇳🇿 New Zealand.

Unlike its slower-moving relatives in the Molidae family, the slender sunfish is more agile, feeding primarily on fast-moving squid from the Ommastrephidae family, as well as other planktonic crustaceans. This indicates its capability as a faster-moving predator in comparison to its relatives which favor jellyfish and slower prey.

Historically, the first specimen in South 🇦🇺 Australia was found at Aldinga in 1944, leading to the creation of a display model for the South 🇦🇺 Australian Museum. The species also occasionally strands at South 🇦🇺 Australian locations such as Port Willunga, Netley, and West Beach, with successful rescues being recorded.

The genus name, Ranzania, honors Camillo Ranzani, an Italian priest and naturalist who lived between 1775 and 1841.