Platichthys flesus (Linnaeus, 1758)

Freyhof, Jörg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, GmbH, Berlin / Boston: De Gruyter : 812-813

Platichthys flesus

Common name. Flounder.

Diagnosis. Only flatfish entering freshwater habitats in West Asia. Distinguished from other species of flatfishes occasionally entering freshwaters in Mediterranean and Black Sea basins by: ○ about 80 total lateral-line scales / ○ enlarged scales along dorsal and anal bases / ● bony tubercles along lateral line / ○ 51–66½ dorsal rays / ○ 35–45½ anal rays / ○ eyes on right side (but, in North Sea, up to 40 % of individuals may have eyes on left side). Size up to 500 mm SL.

Distribution . Black Sea, Mediterranean, eastern Atlantic northeast to White Sea. Introduced in Caspian Sea and Great Lakes of North America. Occasionally recorded up to 650 km upstream in Rhine, in western Asia only in estuarine habitats.

Habitat. Shallow, marine, and estuarine mud and sand bottoms; rarely enter freshwaters in West Asia.

Biology. Males spawn first time at 2–3 years, females at 3–4 years. Migrates to sea in October–December. Spawns at sea in deep water, in January–June. Eggs and larvae pelagic and drift with current. At about 10 mm SL, left eye moves to right side, pigmentation develops, and juveniles become benthic. Pelagic larvae migrate to brackish and freshwater habitats with tidal currents, moving up water column during high tide and to bottom during low tide. First pelagic flounder is usually recorded in estuaries in March. Juveniles begin to migrate upstream into freshwater to feed by mid–April. Few individuals enter brackish or fresh water. Spawning adults do not return to brackish or freshwater but remain at sea. Feeds on small fish and benthic invertebrates.

Conservation status. LC.

Remarks. The taxonomy of founders needs a critical revision. Several species may be confused under the name P. flesus . Platichthys luscus is occasionally used as a valid name for flounders from the northeastern Mediterranean and Black Sea basin flounders. However, we could not find any data to support this view.

Further reading. Voronina 1999 (systematics).

Figures

Platichthys flesus

Distribution