blenny, common name of various species of extremely numerous small fishes belonging to the families Blenniidae (combtooth blennies) and Nototheniidae (Antarctic blennies). They are characterized by elongated, tapering bodies and a continuous long dorsal fin. Blennies live among eelgrass in shallow brackish water or freshwater and feed on small invertebrates. Some blennies have scales and some do not; certain species have fleshy filaments on the head. Tropical Atlantic species include the striped blenny (found as far north as New York) and the more southerly freckled blenny. The kelpfishes are a closely allied Pacific family. Those that live in kelp beds are mottled in coloration and those found in eelgrass are silver and green, matching their environment. The closely related wolffishes of the family Anarhichadidae, with large, tusklike teeth, are found in arctic Atlantic waters. They average 3 ft (90 cm) in length and are good food fishes, sold commercially as "ocean catfish." Blennies are classified in the phylum Chordata, subphylum Vertebrata, class Osteichthyes, order Perciformes, families Blenniidae and Nototheniidae.

Any of numerous and diverse fishes (suborder Blenniodei, order Perciformes) that are mostly small, marine species found from tropical to cold seas. Blennies are slim, ranging from moderately elongated to very long and eel-like. Their habitats range from rocky pools to sandy beaches, reefs, and beds of kelp. Many live in shallow water, but some range to depths of about 1,500 ft (450 m). Some are mainly herbivores; others are partial or complete carnivores. They are generally unobtrusive and of little economic importance.

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