The chain pipefish, Syngnathus louisianae, is a member of the family Syngnathidae. The IRL contains a few members of this group, including five other pipefishes and three seahorse species. Syngnathids are characterized by a body divided into tail and trunk portions, and a head with a prominent snout (Robins & Ray 1986). The length of this snout is one of the main factors used to cluster pipefishes into three groups. The chain pipefish is a long-snout species, with a head to snout ratio of less than 1.9 (Robins & Ray 1986). The common name of the species is derived from the long row of chainlike diamond-shaped marks along the lower side. The dorsal fin of syngnathids is usually aligned with tail and trunk rings. In S. louisianae, the fin is located between the 2nd and 3rd trunk ring, extending up to the 6th tail ring some individuals (Dawson 1972). Other fin ray and meristic counts are as follows: dorsal fin rays = 33-36; trunk rings = 19-21; and tail rings = 36-37 (Robins & Ray 1986).