Slender Sunfish, Ranzania laevis (Pennant 1776)

Other Names: Dwarf Sunfish, Oblong Sunfish, Ranzania, Short Sunfish, Slender Mola, Truncated Sunfish, Trunkfish, Tsunami Fish

A Slender Sunfish, Ranzania laevis, washed ashore in Namibia. Source: J Kemper / Fishbase. License: CC by Attribution-NonCommercial

Summary:

A rare small ocean sunfish with a slender oblong body, a pointed snout with a small oval funnel-like mouth, long pectoral fins, and ‘smooth’ skin covered in tiny hexagonal scales.

Slender Sunfish are dark blue above, brilliant silvery on the sides and below, with variable blue, grey, brown or green stripes and spots, and a series of dark stripes curving below and behind the eye to the underside.

Although rarely seen in coastal waters, large shoals occasionally strand themselves along Australia's south-west coast. Slender Sunfish are agile and fast swimmers, sufficiently powerful to breach out of the water (Nyegaard et al. 2017).

Video of a Slender Sunfish leaping from the water and a school stranding in the Canary Islands.

Video of a large school of juvenile Slender Sunfishin the Canary Islands.

Video of a Slender Sunfish.

See inside Ranzania laevis at the Digital Fish Library with 3D MRI images.

Cite this page as:

Bray, D.J. 2024, Ranzania laevis in Fishes of Australia, accessed 18 Jan 2025, https://fishesofaustralia.net.au/Home/species/786

Slender Sunfish, Ranzania laevis (Pennant 1776)

More Info

Distribution	Lizard Island area, Queensland, around southern Australia, to off North West Cape, Western Australia. Elsewhere the species is circumglobal in tropical and warm temperate seas (including Mediterranean Sea, Sea of Marmara, Persian Gulf). Slender Sunfish are fast swimmers, and often travel in large schools well offshore. Although rarely seen in coastal waters, large shoals occasionally strand themselves along the south-west Australian coast.
Features	Dorsal-fin rays 16-20; Anal-fin rays 18-19; Pectoral-fin rays 13; Clavus 21 ossicles. Body depth 49-54% SL; head length about 39% SL. Body relatively slender, more or less oblong in shape,; lips funnel-like, closing as a vertical slit; pectoral fin elongate. Skin smooth with small hexagonal scales or scutes; scales hexagonal with a row of 1–4 short and blunt spines in the central part; scales of similar size, ca. 0.24 mm in diameter; interdigitations along edges of scales tightly articulate them to one another.
Size	The smallest ocean sunfish, reaching a length of only 100 cm TL.
Colour	Dark blue above, brilliant silver on sides and below, with some variably blue, grey, brown or green darkish stripes and spots; series of dark stripes curving below and behind eye to ventral surface.
Feeding	Feeds on zooplankton, especially small crustaceans, along with small fishes and squids.
Biology	The species appears to form large spawning aggregations (Horn et al. 2016).
Fisheries
Conservation	IUCN Red List : Near Threatened
Remarks	Slender Sunfish occasionally strand in their hundreds along Australia's southwest coast. The species prefers warm waters, and schools may be transported south in the tropical Leeuwin Current, before being carried inshore by upwellings and eddies.
Etymology	The specific name is from the Latin laevis (= smooth), presumably in reference to the relatively smooth skin of this species.
Species Citation	Ostracion laevis Pennant 1776. British Zoology 3: 129, pl. 19. Type locality: Cornwall, England.
Author	Bray, D.J. 2024
Resources	Atlas of Living Australia Australian Faunal Directory Catalog of Fishes

Slender Sunfish, Ranzania laevis (Pennant 1776)

References

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