Pipefishes or pipe-fishes (Syngnathinae) are a subfamily of small fishes, which, together with the seahorses and seadragons (Phycodurus and Phyllopteryx), form the family Syngnathidae.

The name is derived from the peculiar form of the snout, which is like a long tube, ending in a narrow and small mouth which opens upwards and is toothless.

This dermal skeleton has several longitudinal ridges, so a vertical section through the body looks angular, not round or oval as in the majority of other fishes.

Most species of pipefish are usually 35–40 cm (14–15.5 in) in length and generally inhabit sheltered areas in coral reefs or seagrass beds.

Due to their lack of strong swimming ability pipefish are often found in shallow waters that are easily disturbed by industrial runoffs and human recreation.

Another factor that affects pipefish populations is their use in traditional Chinese medicine (TCM) remedies, despite the lack of evidence of efficacy beyond placebo.

Syngnathidae in general are in high demand for pseudo-scientific medicinal cures but pipefish are even more exploited because of a belief in their higher level of potency (because they are longer than the more common variety of seahorses).

Pipefishes, like their seahorse relatives, leave most of the parenting duties to the male, which provides all of the postzygotic care for its offspring, supplying them with nutrients and oxygen through a placenta-like connection.

In males without these pouches, eggs adhere to a strip of soft skin on the ventral surface of their bodies that does not contain any exterior covering.

[8] Furthermore, in Corythoichthys haematopterus, similar ritualized mating dances were hypothesized to aid in reproductive synchronization, by allowing the female to assess male willingness to spawn so her eggs are not wasted.

Pregnant male pipefish can absorb nutrients from their broods, in a manner very similar to filial cannibalism found in many other families of fish.

This tends to occur with greater frequency in internal-brooding species of pipefishes than with external-brooding ones due to limitation in male brood capacity.

[14] For example, the polyandrous Gulf pipefish (Syngnathus scovelli) displays considerable sexual dimorphic characteristics such as larger ornament area and number, and body size.