Syngnathoides biaculeatus has a breeding season of between October and April in Moreton Bay, Australia (Takahashi et al. 2003) but year-round in BootlessBay, PNG (Barrows et al. unpub). Males mature and can begin brooding at a length of about 180 mm (Dawson, 1985; Takahashi et al. 2003) although smaller mature males have been observed (Barrows et al., unpub). Brood size for males was comparable to that of other syngnathids, at 60-200 eggs (Takahashi et al. 2003) although ongoing research suggests that larger broods can occur (Barrows et al., unpub). The eggs can vary in colour (they can be clear, white, brown, or green) as they develop and are carried on the abdomen of the male until they hatch (Grant 1978, Takahashi 2000).

Syngnathoides biaculeatus is a poor swimmer, propelling itself by the winnowing action of the dorsal and pectoral fins (Pogonoski et al. 2002). Some individuals have been observed near the surface of the water or jumping out of the water entirely (Dawson 1986, Kuiter 1996). Prey items include shrimps, fish, and amphipods (Nakamura et al. 2003) as well as other tiny crustaceans (Allen and Swainston 1992).

Size