larval growth occurs in the sea. Reproduction Adult fish typically reach sexual maturity at one year and spawning is triggered by changes in day length and temperature. Unless landlocked within a lake, the common galaxias spawns mainly in autumn during spring tides in the tidally influenced reaches of rivers and streams but spawning in winter and spring has occurred. The eggs are laid en masse amongst flooded riparian vegetation by females. Male fish then release sperm into the water and the eggs are fertilised externally. This type of spawning is called polygynandry. Eggs remain attached to the vegetation as the tide recedes. Two types of reproductive strategy occur: the most common is a 'boom bust' strategy whereby spawning occurs in one event and is followed by death (semelparity), or much more rarely spawning occurs in multiple years before death iteroparity. Egg development Eggs (about 1 mm diameter) develop at the base of vegetation for 2–4 weeks. Environmental conditions in the vegetation (particularly temperature and humidity) are critical for successful egg development. Egg mortality occurs from excess exposure to sunlight, predation from mice and spiders, grazing and trampling by livestock, mowing of bankside vegetation in urban areas, and flooding. The following spring tide floods the eggs stimulating them to hatch. Marine life After hatching, the 7-mm-long larvae are swept out to sea and spend 3–6 months in the marine environment. This phase of their lifecycle is little understood, as the larvae are small, transparent, and difficult to locate. The speed and direction of ocean currents play an important role in their dispersal; temperature and food availability are also important in determining how long they spend at sea. This marine dispersal phase is a critical part of the common galaxias's lifecycle, because it gives larvae from different populations or rivers the opportunity to 'connect'. When the juveniles are sufficiently grown, about 30–55 mm in length, they migrate back into fresh water. The juveniles form large shoals as they move through estuaries. Some of their life is spent in the lower reaches of rivers, where they metamorphose, before spending their adult life in suitable freshwater habitat. Some individuals return to the river they were born in (natal homing), but most return to rivers other than their birth site. Freshwater life Following metamorphosis, adult spend around 6 months in fresh water, where they gain sufficient growth and energy to begin investing in reproduction. Males