Pipe Fish, the popular name of the subfamily syngnathince of the lophobranchiate order of marine acanthopterygian fishes, and particularly of the genus syngnathus (Linn.). The characters of the order have been given in the article Lophobranchs. In the subfamily the form is much elongated, and covered with a series of imbricated plates, and the gills are arranged in tufts instead of plates. The genus has a seven-sided body, the snout straight and cylindrical, and without spines; a single dorsal on the middle of the back, not on an elevated plane, the upper border of the back never in the same line with that of the tail; the upper border of the latter either continuous with the lateral line or interrupted where that ends; dorsal surface flat or slightly concave, and the rings of the body 24 to 27; the gill opening is circular and high up, and the ventrals are wanting; the jaws tubular, the mouth at the end; in some species the pectorals, anal, and caudal are wanting; the tail is not prehensile; the head in the same line with the body; the males have a caudal egg pouch under the tail, open in its whole extent.

About 20 species are described, of which in Europe the best known is the great pipe fish (S. acus, Linn.), sometimes called needle fish; this has all the fins except the ventrals; it is found at high or low water, swimming slowly among sea weeds, feeding on small crustaceans and mollusks, marine worms, insects, and roe of fishes. In the male the posterior part of the abdomen is broader than the rest, with two soft flaps folding together and forming a kind of pouch for the reception of the eggs, which, it is believed, are placed there by the female; it is greatly attached to the young, which also, when small, are said to take refuge in the pouch; it is interesting to observe that whenever among fishes unusual care is taken of the eggs or young, this duty is performed by the males. It attains an average length of 18 in., and is pale brown, transversely barred with darker brown; the tail is fanshaped. In America is the S. Peckianus (Sto-rer), which attains a length of 12 in.; the color is olive brown, with numerous transverse darker bars, and yellowish below; pouch present, and all the fins except the anal, or the latter is exceedingly minute; eyes prominent and very movable.

Another species, from New England and New York, less common, is the brown pipe fish (S. fuscus, Storer), of a general brownish color. It is very easy to see in the aquarium that the tail is not the sole nor the principal organ of locomotion in these fishes, and many species have no fin but the dorsal; when desirous of rapid progress, they move the body very much like an eel, but in ordinary locomotion the dorsal is the chief motor organ; this may be seen to make short and quick vibratory movements which pass in spiral waves along its border, like the screw of a propeller, and might well have suggested this motive power to naval architects. They have also a remarkable power of moving the eyes, even through an arc of 90°, and each independently of the other; this faculty is possessed by the family. - Other acanthopterous species of the family aulostomidae are also called pipe fishes; these are characterized by the prolongation of the bones of the face into a long tube, at the end of which is the mouth; the ribs are short or absent, and the intestines have neither great dilatations nor many folds.

In Jistularia (Linn.) the mouth is small, with a nearly horizontal gape; the body long and slender, the head forming one half or one third of the total length; branchiostegal rays six or seven; dorsal single and simple, opposite the anal; teeth small; one or two jointed filaments, sometimes as long as the body, issuing from between the deep forks of the caudal; air bladder very small; scales invisible. The serrated pipe fish (F. ser-rata, Bloch) attains a length of 28 to 30 in., of which the caudal filament is 10 or 12 in.; color light drab, with a narrow brownish blue band along the sides, the throat white, and the abdomen and irides silvery; the snout with longitudinal serrated ridges; the lower jaw the longer and somewhat curved upward, with a fleshy protuberance at the chin; the shoulders covered with horny plates; the dorsal and anal triangular, pectorals quadrangular, ventrals very small and about midway between pectorals and anal; it is found from Massachusetts to the coast of Brazil. The tobacco-pipe fish (F. tabacaria, Bloch), also American, is smaller, brownish with a row of pale spots, with the abdomen white in the middle, and the orbits spiny.

In centriscus (Linn.) there is the tubular snout, but the body is oval and compressed, trenchant on the abdomen; there is a spinous dorsal very far back, with a strong first spine, and a soft dorsal behind it; the body is covered with small scales. The G. scolopax (Linn.), called sea snipe and trumpet fish, is common in the Mediterranean; it is 4 or 5 in. long, reddish on the back and sides, and silvery on the belly, sometimes with a golden tinge; its flesh is delicate and esteemed. The food of all these fishes consists of minute crustaceans and other marine animals.

Pipe Fish (Syngnathus Peckianus).

Serrated Pipe Fish (Fistularia serrata).