Marine life  /  Flatfish  /  Tonguefish
Reviewed 2026-09-06
Species entry

Tonguefish

Cynoglossidae

A leaf-shaped flatfish with both eyes on the left and fins running unbroken to a point.

Size
8 to 30 cm
Depth
2–30 m
Habitat
Sand and silt
Active
Night
Range
Indo-Pacific
Rarity
Lembeh Strait
3 stars of 5, a good week should turn one up
SP-01
tonguefish · full body · habitat
4:3 · min 2400px

A flatfish shaped like a long leaf, from about 8 cm in the smaller species to around 30 cm in the larger ones. Both eyes are on the left side and set close together, the mouth is small and hooked round onto the underside, and the dorsal and anal fins run without a break into the tail, so the animal ends in a point rather than in a separate fin. There are no pectoral fins. Colour is a plain brown or grey, occasionally with faint bars.

It lies buried in sand and silt through the day and moves across the surface at night, driven by a ripple running along the fin fringe. That movement is the quickest separation from the soles and flounders on the same ground, which settle and flap rather than glide. Species identification rests on fin ray and scale counts and on the number of lateral lines, none of which a photograph resolves, so records are normally kept at the family.

Recorded from about 2 to 30 m on soft sediment.

Where to find:

LocationRarity Best monthsDepthHabitat
Lembeh Strait Indonesia editorial estimate
3 stars of 5, a good week should turn one up
Year-round
2–30 m
Sand and silt
Anilao Philippines editorial estimate
3 stars of 5, a good week should turn one up
Year-round
2–30 m
Volcanic sand
Ambon Indonesia editorial estimate
3 stars of 5, a good week should turn one up
Year-round
2–30 m
Harbour sand and silt
Dauin & Dumaguete Philippines editorial estimate
3 stars of 5, a good week should turn one up
Year-round
2–30 m
Volcanic sand

Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.

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