Cleisthenes pinetorum is a species of flatfish in the family Pleuronectidae, found in the cold-temperate coastal waters of the northwest Pacific Ocean, particularly around northern Japan, the Sea of Okhotsk, and parts of the Russian Far East. The genus name Cleisthenes is derived from Greek, historically used as a personal name meaning “famous strength,” while the species epithet pinetorum comes from Latin pinus (“pine”) with the suffix -etorum indicating “grove,” likely referencing the bay of Matsushima which means Pine Island in Japanese. This species is sometimes referred to as a type of flounder and is related to other right-eyed flounders commonly consumed in East Asian cuisines.

Like other members of the Pleuronectidae, Cleisthenes pinetorum undergoes a distinctive developmental transformation in which one eye migrates to the opposite side of the head, resulting in a flattened body adapted for life on the seafloor. It inhabits sandy or muddy benthic environments where it feeds on small invertebrates such as crustaceans, worms, and mollusks. Its body is typically oval and laterally compressed, with coloration that provides camouflage against the substrate.

As a food source, Cleisthenes pinetorum is consumed in regional Japanese and northern Pacific cuisines, where it may be prepared grilled, simmered, or dried. The flesh is white, lean, and mildly flavored, similar to other flounders, making it suitable for a variety of cooking methods including broiling and stewing. Smaller individuals may be dried whole, while larger fish are filleted for direct culinary use.

Nutritionally, the flesh of Cleisthenes pinetorum is a good source of high-quality protein and contains low levels of fat compared with oily fish species. It provides essential nutrients such as vitamin B12, phosphorus, and selenium. Like other marine fish, it contains small amounts of omega-3 fatty acids and may also yield bioactive peptides upon digestion or processing, which have been studied for potential antioxidant and antihypertensive effects in experimental settings.