Broad physiological tolerances, rapid growth, early maturation and exceptional fecundity are primary factors in the success of carp as an invasive species in Australia. Control measures which affect their spawning success may have the greatest potential for limiting population growth. The development of control methods is constrained though, by a lack of information on key aspects of the early life history and reproduction of carp in Australia. Accordingly, the present study investigated fecundity, spawning patterns and the tolerance of eggs to salinity and dehydration. Adult and juvenile carp were collected during October to February from wetland sites in the lower Murray Darling Basin. Spawning activity on the Chowilla floodplain, as determined from lapillus microstructure, occurred from late September until late December in three wetlands. Reproduction peaked in October and thereafter was infrequent and limited. This peak in reproduction coincided most strongly with variation in flow, water level, photoperiod, wind speed, air temperature and water temperature, and was largely synchronous among wetlands over a 60 km range. Thus, it appears that carp may be responding to regional rather than local environmental stimuli. Growth rates varied from 0.37-0.54 mm d^-1 among wetlands and there were striking temporal and spatial differences in the numbers and distribution of fish within wetlands. Fecundity was best estimated by gonad weight in ripe female carp collected from Swan Reach, and averaged 43,000 eggs per kilogram of fish. The sex ratio of males to females was 1:1.7. Although Murray cod eggs were used as a substitute for carp eggs in the egg-tolerance trials, two points concerning the tolerance of carp eggs to dehydration and salinity can be inferred from them. They are; carp eggs will die within hours, rather than days of exposure and salinity probably will not limit carp recruitment in most inland lakes and rivers of Australia. These data may be incorporated into a trial to investigate the feasibility of a timed water draw-down in South Australia and its effect on egg survival and carp recruitment.