Clidoderma asperrimum, commonly called roughscale sole, is a species of marine flatfish in the family Pleuronectidae. It inhabits cold and temperate coastal waters of the northwest Pacific Ocean, particularly around Japan, the Sea of Okhotsk, and adjacent Russian waters. The genus name Clidoderma derives from Greek elements (kleidion, meaning collarbone and derma, meaning skin) referring to structural features of the fish’s body surface, while the species epithet asperrimum comes from Latin asper, meaning “rough,” referring to the relatively rough texture of the skin or scales. This fish is sometimes referred to as the roughscale sole because of the coarse nature of its body surface compared with smoother flounder species.

Like other members of the family Pleuronectidae, Clidoderma asperrimum undergoes a distinctive developmental transformation known as metamorphosis. During early larval life it resembles a typical symmetrical fish, but as it matures one eye migrates to the opposite side of the head, producing the characteristic flat body adapted for life on the seafloor. Adults rest on sandy or muddy substrates with the eyed side facing upward, allowing them to blend into the surrounding environment. This camouflage helps them avoid predators and ambush prey such as small fish, crustaceans, and benthic invertebrates.

As a food source, Clidoderma asperrimum is harvested in regional fisheries of the northern Pacific and used in various seafood dishes. The flesh is white, firm, and relatively mild in flavor, characteristics typical of many flatfish. It can be prepared by grilling, pan-frying, steaming, simmering, or as sashimi, and it is sometimes used in soups or stewed dishes in coastal cuisines. In Japan and neighboring regions, flatfish species are often valued for their delicate texture and clean taste.

Nutritionally, the meat of Clidoderma asperrimum is high in protein and low in fat, providing essential amino acids along with minerals such as phosphorus and selenium. Like many marine fish, it contains small amounts of omega-3 fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which contribute to cardiovascular and neurological health. Bioactive compounds in flatfish muscle may also include small peptides produced during digestion that have been studied for antioxidant and antihypertensive potential.