In this study, 36 males, 33 females and 15 juveniles of the common or weedy seadragon Phyllopteryx taeniolatus, a syngnathid fish endemic to the waters of southern Australia, were identified using visual implant fluorescent elastomer tags and pattern of appendages and their reproductive cycle and growth was studied from May 2001 to June 2002. Brooding males were present for a period of >6 months, from June–July to early‐January. The percentage of males that were pregnant in the studied areas peaked in November–December, near the end of the breeding season. Two pregnancies were reported for some males. Ten recruits were identified from November to June. Growth rates for young‐of‐the‐year, young of the previous year, males and females were measured. The von Bertalanffy growth constant K was estimated at 0·098 month−1.