any of more than 150 species of elongated fishes allied to the sea horses, in the family Syngnathidae (order Gasterosteiformes). Pipefishes are very slender, long-bodied fishes covered, like sea horses, with rings of bony armour. They have long, tubular snouts and small mouths, a single dorsal fin, and, usually, a small tail fin. Depending on the species, they may range in length from about 2.5 to 50 cm (1 to 20 inches)
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