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Phylum Chordata > Subphylum Vertebrate > fishes > Order Pleuronectiformes
Tongue-soles
Family Cynoglossidae
updated Sep 2020

if you learn only 3 things about them ...
Small and flat, they are often mistaken for flatworms!
Eyes on left side of the body. Tail, dorsal and anal fins joined all around the body.
Found beneath the sand. Watch your step!

Where seen? These tiny flatfishes are sometimes seen on our Northern shores, among seagrasses, buried in sand or hovering over the surface.

What are tongue-soles?
Tongue-soles are flatfishes belonging to the Family Cynoglossidae. According to FishBase: the family has 3 genera and 110 species. They are found in all warm oceans, most species in shallow waters or near river mouths. One group (Symphurinae) are found in very deep waters 1,000m or more. In Greek, 'kyon' means 'dog' and 'glossa' means 'tongue'.

Features:
To about 18cm, those seen about 3-6cm. Both eyes on the left side, usually very small and close together. Body flat and oval, tapering at the tail, like an elongated tear-drop shape. The tail fin is joined and merges seamlessly with the dorsal and anal fins. There are no spines in all the fins. The dorsal fin starts at or infront of the eyes. It lacks pectoral fins. The teeth are tiny and usually only on the blind side. The eyed side usually has an even pattern of pale spots and matches the colour of its surroundings. Patterns may vary even within the same species. And patterns are often obscured by a layer of sand. Species are difficult to positively identify in the field or from photographs without closer examination of small features on the body.

Sometimes confused with other flatfishes. Here's more on how to tell apart the flatfish families commonly seen. Tiny, flat and fast, they are also sometimes mistaken for flatworms.

A tiny one.
Changi, Oct 08

Changi, Jun 05

Seringat-Kias, Feb 11
 
What do they eat? Like other flatfishes, they are ambush predators. Lying in wait for prey, just beneath the sediment or sand, with only the eyes sticking out.

Human uses: Many large tongue-sole species are commercially important as food. Elsewhere, some species can reach 40cm long.

Tongue-soles on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores


Pasir Ris, Jul 18
Shared by Richard Kuah on facebook.



Changi CP7, Jan 21

Photo shared by Marcus Ng on facebook.

Changi, Apr 09

Photo shared by Loh Kok Sheng on flickr.


East Coast, Aug 18

Photo shared by Loh Kok Sheng on facebook.
 

 
East Coast, Dec 08

Photo shared by Loh Kok Sheng on his blog.


East Coast, Aug 18

Photo shared by Loh Kok Sheng on facebook.
 

 
Tanah Merah, Jan 10

Photo shared by James Koh on flickr.

Family Cynoglossidae recorded for Singapore
from Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore.
^from WORMS

  Family Cynoglossidae
  Cynoglossus arel
Cynoglossus bilineatus
Cynoglossus blochii=^Paraplagusia blochii
Cynoglossus borneensis=^Plagusia borneensis=^Cynoglossus trulla
Cynoglossus cynoglossus
Cynoglossus grandisquamis
Cynoglossus kopsii
Cynoglossus lingua
Cynoglossus macrolepidotus
Cynoglossus puncticeps
(Speckled tongue-sole)
Cynoglossus sibogae
Cynoglossus sumatranus=^Plagusia sumatrana=^Cynoglossus cynoglossus

Paraplagusia bleekeri
(Bleeker’s fringelip tongue-sole)
Paraplagusia bilineata
(Double-lined tongue-sole)

Links

References

  • Kelvin K. P. Lim & Tan Heok Hui. Bleeker’s fringelip tongue-sole at East Coast. 29 March 2018. Singapore Biodiversity Records 2018: 33-34 ISSN 2345-7597. National University of Singaporec.
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